Dual-zoned absorbent webs

ABSTRACT

A dual-zoned, three-dimensional, resilient absorbent web is disclosed which is suitable as body-side liner for absorbent articles such as feminine pads, diapers and the like. When used as a liner in absorbent articles, the dual-zoned web combines the advantages of apertured films and soft, nonwoven cover layers in one structure while still being inherently hydrophilic. The liner comprises a web of wet-resilient, hydrophilic basesheet having a three-dimensional topography comprising elevated regions onto which hydrophobic matter is deposited or printed and a plurality of spaced apart depressed regions. In a preferred embodiment, the hydrophobic matter applied to the elevated regions of the basesheet comprises hydrophobic fibers in a contiguous nonwoven web which has been apertured or provided with slits or other openings, such that the apertures or openings overlay a portion of the depressed regions. The elevated hydrophobic regions enhance dry feel and promote fluid flow toward the lower hydrophilic regions, which comprise the exposed depressed regions of the basesheet. The basesheet is preferably in liquid communication with underlying absorbent material, most preferably a stabilized airlaid cellulosic material or compressed stabilized fluff such that the absorbent material can wick fluid out of the basesheet by capillary action. When soft, hydrophobic fibers are deposited on the elevated regions, the liner also has a soft, cloth-like feel in addition to a dry feel in use.

BACKGROUND OF THE INVENTION

[0001] Absorbent articles are typically used in contact with skin. Someabsorbent articles such as disposable diapers, feminine pads, pantyliners, incontinence pads and the like are held in contact with skin toabsorb body liquids or exudates, while other absorbent materials such aspaper towels, hand towels, and wipers may be held in the hands to absorbliquid on the skin or other surfaces. In virtually every case, it isdesired that the absorbent article or material keep liquids off the skinto provide a clean, dry feel and to reduce skin health problems thatarise from excess hydration or from contact with harmful biological orchemical materials in the liquid being absorbed.

[0002] While paper towels and wipers are often composed of a homogenousmaterial, such as an entirely cellulosic web, absorbent articlesintended to absorb body fluids typically have at least three layers ofdifferent materials. Next to the user's skin is a topsheet layer,sometimes herein referred to as a liner, body-side liner or cover sheet.Beneath the topsheet is the absorbent core that is designed to retainliquid, and beneath the absorbent core is a fluid-impervious backsheetthat prevents leakage and maintains the integrity of the product. Thetopsheet should feel soft and should have high liquid permeability toallow body fluid such as urine, menses, or runny bowel movement to beabsorbed and transported away from the skin to reach the centralabsorbent core. Ideally, the topsheet provides a “dry touch” or “dryfeel” by preventing liquid from flowing back to the skin. It is alsodesirable that the topsheets have high wet resiliency to maintain theirbulk and shape when wet.

[0003] Traditional hydrophilic cover materials or topsheets in contactwith the skin can serve effectively to transport body fluids into theabsorbent core, but they cause a wet feel against the skin of the userand may adversely affect skin health. Further, they may wick liquid inthe plane of the layer, allowing liquid to approach the edges of theabsorbent article and possibly leak or seep out.

[0004] To achieve the goal of softness and a dry feel in topsheets ofabsorbent articles, many manufacturers have turned to nonwoven fabricsmade of hydrophobic fibers for the body-contacting topsheet. While theuse of hydrophobic nonwoven fabrics may have resulted in improved dryfeel, the hydrophobic material hinders wicking into the absorbent core,offers little absorbent capacity and reduces liquid permeability.Further, the poor absorbency of most hydrophobic materials causes anyliquid retained therein to be easily squeezed out by body motion of thewearer.

[0005] Others have sought to improve the poor wicking and absorbentproperties of hydrophobic materials by applying a finish comprisingsurfactants on the surface of the hydrophobic fibers. This approach mayoffer some benefits when the article is first wetted, but thesurfactants tend to be washed away, resulting in poorer performance uponfurther wetting.

[0006] In the case of absorbent pads for feminine care, two distinctapproaches involving hydrophobic topsheets or covers are common. Oneapproach is to use a soft, cloth-like nonwoven hydrophobic material,which increases comfort but has the drawback of poor intake of menses.Another approach is to use an apertured plastic film of hydrophobicpolymer or other materials. The hydrophobic cover material repels manybody fluids, while the apertures allow wicking away from the cover intothe absorbent material beneath.

[0007] In theory, the hydrophobic apertured material should allow theuser's skin to remain relatively dry while allowing wicking in thez-direction (normal to the plane of the cover) into the underlyingabsorbent core. In practice, hydrophobic apertured films present anumber of problems. Apertured films have the drawback of being dislikedby some users for their plastic feel and for their poor absorbency.Their hydrophobic nature resists transport through the material,possibly delaying wicking into the absorbent core. Likewise, pockets orpools of liquid may form between the film and the user's skin. In theabsence of hydraulic pressure or physical compression, menses inparticular may pool on the hydrophobic surface and not penetrate intothe apertures, especially if there is a significant interfacial gapbetween the cover and the underlying absorbent material.

[0008] Therefore there is a need for an improved topsheet material whichprovides the clean feel said to be characteristic of hydrophobictopsheet materials, while also providing for rapid z-direction(depthwise) transport of liquid through the topsheet into the underlyingabsorbent core, a characteristic more typical of hydrophilic materials.Preferably, these absorbent topsheets also have wet resiliency andabsorbency properties which persist upon multiple insults of urine orother liquids.

SUMMARY OF THE INVENTION

[0009] The present invention pertains to composite, resilient materialsthat offer the once-thought mutually exclusive benefits of highabsorbency and a clean, dry feel when used as skin-contacting layersthat absorb body fluids or other liquids.

[0010] In copending U.S. application, Ser. No. 08/614,420, “WetResilient Webs and Disposable Articles Made Therewith,” by F.-J. Chen etal., herein incorporated by reference, a novel wet-laid tissue web istaught having unusually high bulk, wet resiliency, in-planepermeability, and absorbency. The unusual properties of this materialare achieved through a combination of high yield fibers, wet strengthadditives, and noncompressive drying of a molded, three-dimensionalstructure. The three-dimensional structure of this material does notcollapse readily when wetted and thus reduces the contact area with theskin when wet, contributing to a relatively dry feel. It has been foundthat the inherently hydrophlic material of this previous invention andrelated materials can be made substantially more useful in personal carearticles by the selective addition of hydrophobic material which canimpart increased dry feel and, in some embodiments, improved softness.With hydrophobic material deposited on the uppermost, body-contactingregions of the three-dimensional hydrophilic web, the highestbody-contacting regions are made substantially hydrophobic to increasethe sensation of a clean, dry feel, while a plurality of hydrophilicregions in said web remain accessible to body fluids, allowing liquidsto be wicked away from the body and into an absorbent medium. Thus, dryfeel and high absorbency are achieved in a single unitary layer or in asingle composite structure which may be a laminate of hydrophobic andhydrophilic materials. The hydrophobic material is bonded or integrallyattached to the basesheet. Improved disposable absorbent articlescomprising such materials include feminine pads and panty liners,incontinence products such as diapers and liners, bed pads, disposablediapers, pull-ups or disposable training pants, disposable menstrualpants, poultry pads, disposable sweat bands or pads, breast pads, odorabsorbing pads for shoes, towels, moisturized wipes, wipers, medicalpads, bandages and sterile pads for wounds, disposable garments, linersfor helmets or other protective or athletic gear, pads for use in waxingautomobiles and other surfaces, and so forth. A simple example of anabsorbent article containing a topsheet, absorbent core and a backsheetis illustrated in U.S. Pat. No. 3,809,089 issued May 7, 1974 to Hedstromet al., which is hereby incorporated by reference.

[0011] In general, it has been discovered that the addition ofhydrophobic agents or materials on relatively elevated portions of onesurface of a three-dimensional, wet resilient fibrous web, said webpredominantly comprising intrinsically hydrophilic fibers, can enhancethe suitability of such webs for use in absorbent articles by reducingthe amount of fluid that can remain in contact with the skin or flowback to the skin during use as an absorbent article, thus resulting inan improved dry feel. Certain hydrophobic materials such as short finesynthetic fibers can provide a pleasant soft, fuzzy, and dry feel, whileothers such as hydrophobic resins, gels, emulsions, waxes, or liquidscan increase the apparent smoothness or lubricity of the surface andimprove the tactile properties.

[0012] Suitable basesheets can be prepared from aqueous slurries ofpapermaking fibers with known papermaking techniques. The fibers may bederived from wood or other sources of cellulose and preferablycontaining a portion of high yield or other wet resilient pulp fibersand an effective amount of wet strength agents. The basesheet can betextured by through-drying on a three-dimensional fabric or other meansknown in the art and preferably non-compressively dried to give athree-dimensional structure. The inherent stiffness of wet resilientpulp fibers may be reduced, if desired, by incorporation of a suitableplasticizer such as glycerol or by mechanical treatment such asmicrostraining, dry creping, or calendering.

[0013] Through-drying fabrics well suited for formation ofthree-dimensional webs are disclosed in U.S. Pat. No. 5,429,686, issuedto Chiu et al., “Apparatus for Making Soft Tissue Products,” issued Jul.4, 1995, herein incorporated by reference. Other methods such as wetmolding, forming on three-dimensional forming fabrics, drying onnonwoven substrates, rush transfer onto embossing fabrics, embossing,stamping, and so forth may be used to create useful three-dimensionalstructures. The basesheet may be formed as a unitary multilayerstructure in which various plies are well bonded and intimatelyconnected to each other. Unitary multilayer basesheets may be formedusing layered or stratified headboxes in which two or more furnishes areprovided into separate chambers of a headbox, or they may be formedusing separate headboxes by couching the wet webs together prior todrying in order to allow extensive hydrogen bonding to develop betweenthe plies during drying, or they may be formed during air-laying byvarying the composition of the fibers and additives imparted to web.Multilayer sheets allow better control of physical properties bytailoring the material composition of each layer. For example, a unitarymultilayer basesheet useful for the present invention would have anupper layer, corresponding to the upper surface of the basesheet, and atleast one remaining layer below said upper layer and integrally attachedthereto, preferably through hydrogen bonds formed between cellulosicfibers during drying, wherein said upper layer differs from at least oneremaining layer of the basesheet in terms of material composition. Thedifference in material composition may be due to differences in fiberspecies (for example, percentage of hardwood versus softwood); fiberlength; fiber yield; fiber treatment with processes which change fibermorphology or chemistry such as mechanical refining, fiberfractionation, dispersing to impart curl, steam explosion, enzymatictreatment, chemical crosslinking, ozonation, bleaching, lumen loadingwith fillers or other chemical agents, supercritical fluid treatment,including supercritical fluid extraction of agents in the fiber orsupercritical fluid deposition of solutes on and into the cell wall, andthe like. The difference in material composition between the upper layerand at least one other layer in the basesheet also may be due todifferences in added chemicals, including the type, nature, or dosage ofadded chemicals. The chemicals added differentially to at least onelayer of the web may include debonding agents, anti- bacterial agents,wet strength resins, starches, proteins, superabsorbent particles, fiberplasticizers such as glycols, colorants, opacifiers, surfactants, zincoxide, baking soda, silicone compounds, zeolites, activated carbon, andthe like. In a preferred embodiment, the basesheet structure has a wetresilient, noncompressively dried lower layer, preferably composed ofsoftwood fibers, preferably including at least 10% of high yield fibersuch as spruce BCTMP, and a soft upper layer containing a portion offiner fibers such as chemically pulped hardwoods. The multilayerbasesheet structure is unitary, meaning that the two layers areintimately connected or bonded together. For example, a two-layerunitary basesheet could be formed with a layered headbox or by couchingtogether two wet sheets prior to drying to form intimate contact andhydrogen bonding between the two layers.

[0014] The portion of the surface area treated with hydrophobicmaterials should be great enough to provide an effective improvement incomfort, which will in part depend on the specific product. Accordingly,the fraction of the basesheet surface covered by hydrophobic materialcan be about 5% or greater, more specifically about 10% or greater, morespecifically about 20% or greater, more specifically about 30% orgreater, and still more specifically from about 40% to about 75%. Theportion of the surface area of the basesheet that remains essentiallyhydrophilic can be about 10% or greater, more specifically about 20% orgreater, more specifically about 30% or greater, more specifically about40% or greater, more specifically from about 20% to about 90%, and stillmore specifically from about 50% to about 90%. For effective fluidremoval, the lateral width of the depressed hydrophilic regions shouldbe about 0.1 mm or greater, more specifically about 0.5 mm or greater,and still more specifically about 1 mm or greater. The spacing betweendepressed hydrophilic regions can be about 0.4 mm or greater, morespecifically about 0.8 mm or greater, and still more specifically about1.5 mm or greater. The minimum width of the elevated regions can beabout 0.5 mm or greater, more specifically about 1 mm or greater, andstill more specifically from about 1 to about 3 mm.

[0015] In one preferred embodiment, the hydrophobic matter comprises asubstantially contiguous network of hydrophobic fibers having aplurality of macroscopic openings such that a portion of the depressedregions of the basesheet are aligned with openings in the overlayingnetwork of hydrophobic fibers to allow body exudates to pass through themacroscopic openings into the basesheet. A macroscopic opening isdefined as an opening that is large relative to the intrinsic pore sizeof the material. In a typical spunbond or bonded carded web, forexample, a macroscopic opening would appear to the eye to be adeliberately introduced hole or void in the web rather than acharacteristic pore between adjacent fibers, and specifically could havea characteristic width of about 0.2 mm or greater, about 0.5 mm orgreater, about 1 mm or greater, about 2 mm or greater, about 4 mm orgreater, about 6 mm or greater, or from about 1 mm to about 5 mm. Thecharacteristic width is defined as 4 times the area of the aperturedivided by the perimeter.

[0016] The nonwoven web may be made from synthetic fibers, as is knownin the art, and may be a spunbond web, a meltblown web, a bonded cardedweb, or other fibrous nonwoven structures known in the art. For example,a polyolefin nonwoven web such as a low basis weight spunbond materialcould be provided with apertures through pin aperturing; perf embossingand mechanical stretching of the web; die punching or stamping toprovide apertures or holes in the web; hydroentangling to impartapertures by rearrangement of the fibers due to the interaction of waterjets with the fibrous web as it resides on a patterned, textured orthree-dimensional substrate that imparts a pattern to the web; waterknives that cut out desired apertures or holes in the web; laser cuttersthat cut out portions of the web; patterned forming techniques, such asair laying of synthetic fibers on a patterned substrate to impartmacroscopic openings; needle punching with sets of barbed needles toengage and displace fibers; and other methods known in the art.Preferably, the openings are provided in a regular pattern over at leasta portion of the topsheet of the absorbent article.

[0017] Preferably, the openings in the network of hydrophobic fibers arespaced and registered with respect to the structure of the basesheetsuch that a predetermined fraction of the openings are largelysuperposed over depressed regions of the basesheet. An opening is saidto be largely superposed over a depressed region if at least half of thearea of the macroscopic opening resides over a depressed region of thebasesheet. The predetermined fraction of the openings that are largelysuperposed over depressed regions can be about 0.25 of greater, 0.4 orgreater, 0.5 or greater, 0.7 or greater, 0.8 or greater, or from about0.4 to about 0.85. The contiguous network of hydrophobic matter islaminated to or otherwise physically joined with the underlyingbasesheet. Preferably, the network of hydrophobic fibers is attached tothe basesheet by means of adhesives and related agents, including hotmelts, latexes, glues, starch, waxes, and the like, which adhere or jointhe upper regions of the basesheet with adjacent portions of theoverlaying network of hydrophobic fibers. Preferably, adhesives areapplied only to the most elevated portions of the basesheet to effectthe bonding between the hydrophilic basesheet and the network ofhydrophobic fibers with macroscopic openings therein, leaving thedepressed regions substantially free of adhesives. Adhesive applicationcan be through meltblown application of hot melt glues and thermoplasticmaterials, spray or swirl nozzles of melted or dissolved adhesives,printing of adhesive material onto one or both surfaces before joining,and the like. If adhesives are applied directly to the basesheet bymeans of spray, mist, aerosol, or droplets in any form, prior to contactof the basesheet with the hydrophobic matter, then it is desirable touse a template or patterned shield to prevent application of adhesive tothe depressed regions of the basesheet and to ensure that adhesives arepreferentially applied to the elevated portions of the basesheet.

[0018] For improved comfort, the network of hydrophobic fibers use inthe above-mentioned embodiment preferably is one that is perceived assoft and conformable when next to the skin.

[0019] For optimum efficiency in the embodiment comprising a nonwovenweb, the apertures or openings in the web should be arrayed in a patterncorresponding to the array of depressed regions in the tissue basesheet,or should correspond to a subset of the depressed regions of thebasesheet. Applicant have found a useful means for providing aperturesin a nonwoven web in a pattern which corresponds geometrically to thedepressed regions of a molded, three-dimensional basesheet wherein thebasesheet was molded on a foraminous textured substrate such as athree-dimensional through-drying fabric. The method involveshydroentrangling, which is a well known principle involving the use ofhigh pressure water jets to modify a fibrous surface. Basic principlesof hydroentangling are disclosed by Evans in U.S. Pat. No. 3,485,706issued in 1969, and in U.S. Pat. No 3,494,821 issued in 1970, both ofwhich are herein incorporated by reference. Hydroentangling, as is knownin the art, can be used to impart apertures to a nonwoven web. In onewell known technique, the nonwoven web is carried on a textured,permeable carrier fabric. The action of water jets on the nonwoven webas it resides on the textured fabric causes fibers to be moved away fromthe elevated portions of the carrier fabric on which the nonwoven webreside, resulting in apertures where the carrier fabric was elevated. Ifa nonwoven web is placed on the same kind of throughdrying fabric thatwas used to mold a three-dimensional through-dried sheet, preferably anuncreped or only lightly creped sheet in order to preserve texture inthe basesheet, then the high places on the carrier TAD fabric willbecome apertured regions in the nonwoven basesheet. The high portions ofthe TAD fabric will correspond to the depressed regions on the fabricside of the through-dried sheet. Alternatively, if the nonwoven web ishydroentangled against the backside of a three-dimensional TAD fabric,the elevated regions of the TAD fabric's backside will generallycorrespond to the depressed in the air side of the sheet that is throughdried on the TAD fabric. In either case, a nonwoven web can be createdhaving apertures that align with the real physical structure of the TADfabric, namely, with the depressed regions of a through-dried sheet.When the apertured nonwoven material is then attached to thethrough-dried basesheet, the apertures can be aligned with the depressedregions of the basesheet using techniques known in the art, such asphotoelectric eyes or high speed CCD cameras which can view the positionof apertures in the nonwoven web relative to the position of thethrough-dried fabric as the two are brought together, whereupon theposition of one material can be adjusted both in the cross-direction andthe machine direction (e.g., by controlling the speed of one layer or bymachine direction motion of an unwind roll of one material) for properplacement of the two layers together.

[0020] In embodiments comprising contiguous nonwoven webs with spacedapart openings for fluid access to the hydrophilic basesheet, Applicantshave found excellent fluid intake and absorbency results when theabsorbent web is superposed on a separate layer of densified fluff pulpor an air laid cellulosic web, preferably an air laid web stabilizedwith thermosetting materials or crosslinking chemistry such as Kymenewet strength resin. With a densified cellulosic web beneath thebasesheet and hydrophobic matter of the present invention, an insult offluid that enters the hydrophilic basesheet can be pulled out of thehydrophilic basesheet by capillary suction provided that the local poresize of the underlying absorbent layer is small enough. Experiments withdyed water and also with an aqueous egg white mixture have shown thatthe combination of a hydrophobicly treated cellulosic basesheet restingon a densified airlaid web can result in greatly improved intake, withfluid being largely directed into the air laid material and notspreading significantly laterally in the basesheet.

[0021] It has also been discovered that highly calendered versions ofsuch webs are suitable as hand towels. The hydrophobic, originallyuppermost regions are made relatively flat, offering significanthydrophilic areas initially in contact with the wet skin for rapidintake of fluid, but also having the ability to expand after wetting toprovide improved dry feel as the wet, hydrophilic areas retract from theskin relative to the more hydrophobic, elevated regions. Webs so treatedcan achieve the once mutually exclusive goals of having high density foreconomical dispensing and low density once wetted for high absorbency,while also having a dry feel in use.

[0022] Hence, in one aspect, the invention resides in an absorbent webhaving a dry feel when wet, comprising: (a) an inherently hydrophilicbasesheet comprising papermaking fibers and having an upper surface anda lower surface, said upper surface having elevated and depressedregions; and (b) hydrophobic matter deposited preferentially on theelevated regions of the upper surface of said basesheet.

[0023] In another aspect, the invention resides in an absorbentdual-zoned web providing a dry feel in use, said web having an uppersurface comprising a plurality of hydrophobically treated regionssurrounded by inherently hydrophilic cellulosic regions, wherein uponwetting said web expands such that the hydrophobically treated regionsare preferentially elevated relative to said hydrophilic regions.

[0024] In another aspect, the invention resides in an absorbent webhaving a Rewet value of about 1 g or less, comprising: (a) an inherentlyhydrophilic basesheet comprising papermaking fibers and having an uppersurface and a lower surface, said upper surface having elevated anddepressed regions with an Overall Surface Depth of 0.2 mm or greater inthe uncalendered and uncreped state, said basesheet further having a WetCompressed Bulk of at least 6 cc/g; and (b) hydrophobic matter depositedpreferentially on the elevated regions of the upper surface of saidbasesheet.

[0025] In another aspect, the invention resides in an absorbent webhaving a dry feel when wet, comprising: (a) an inherently hydrophilicbasesheet comprising papermaking fibers and having an upper surface anda lower surface, said upper surface having elevated and depressedregions with an Overall Surface Depth of about 0.2 mm or greater; and(b) a substantially contiguous network of hydrophobic fibers having aplurality of macroscopic openings attached to the upper surface of saidbasesheet such that a portion of the depressed regions of the basesheetare aligned with openings in the overlaying network of hydrophobicfibers to allow body exudates to pass through the macroscopic openingsinto the basesheet.

[0026] In another aspect, the invention resides in an absorbent webhaving a dry feel when wet, comprising: (a) an inherently hydrophilicbasesheet comprising papermaking fibers and having an upper surface anda lower surface, said upper surface having elevated and depressedregions, said basesheet preferably having a wet:dry tensile ratio of atleast 0.1; and (b) a contiguous network of hydrophobic matter depositedpreferentially on the elevated regions of the upper surface of saidbasesheet.

[0027] In another aspect, the invention resides in an absorbent articlecomprising a liquid impermeable backsheet, a cellulosic absorbent corein superposed relation with said backsheet, and a liquid permeableabsorbent web, said absorbent web comprising an inherently hydrophilicbasesheet comprising papermaking fibers and having a wet:dry tensileratio of at least 0.1, said basesheet having an upper surface and alower surface, said upper surface having elevated and depressed regionsand hydrophobic matter deposited preferentially on the elevated regions,wherein the basesheet is superposed on the absorbent core with the lowersurface of the basesheet facing the absorbent core.

[0028] In another aspect, the invention resides in an absorbent articlecomprising a liquid impermeable backsheet, a cellulosic absorbent corein superposed relation with said backsheet, and a liquid permeableabsorbent web, said absorbent web comprising an inherently hydrophilicbasesheet comprising papermaking fibers, said basesheet having an uppersurface and a lower surface, said upper surface having elevated anddepressed regions, further comprising an apertured contiguous web ofhydrophobic nonwoven material attached to the upper surface of thebasesheet such that a portion of said apertures overlay the depressedregions of the basesheet, wherein the basesheet is superposed on theabsorbent core with the lower surface of the basesheet facing theabsorbent core.

[0029] In another aspect, the invention resides in calendered, lowdensity structures of previously three-dimensional resilient webs havinghydrophobic matter on the once uppermost regions of one or both sides ofthe web. Without limitation, such articles may serve as suitable handtowels by providing high initial uptake of fluid by the plurality ofhydrophilic regions in the plane of the flat paper during initialwicking, followed by an enhanced dry feel as the dry-feeling treatedareas rise out of the plane of the sheet during wetting. The hydrophobicmatter in such articles may also be used to increase the apparentsoftness or lubricity of the article and be applied in contiguous ordiscontiguous forms.

[0030] In another aspect, the invention resides in a method forproducing an intake material for an absorbent article, comprising thesteps of (a) forming an embryonic paper web from an aqueous slurry ofpapermaking fibers; (b) through-drying the embryonic paper web on athree-dimensional through-drying fabric having a pattern of elevated anddepressed regions; (c) completing the drying of the web; (d) aperturinga nonwoven web by means of hydroentangling, wherein the nonwoven weboverlays a carrier fabric having substantially the same pattern ofelevated and depressed regions as the through-drying fabric of step (b);and (e) joining the apertured nonwoven web with the through-dried paperweb such that the apertures of the nonwoven web are substantiallyaligned with the depressed regions of the through-dried paper web.

[0031] In stating that hydrophobic matter is preferentially deposited onelevated portions of the basesheet, the term “preferentially” impliesthat more hydrophobic matter is deposited on the elevated regions ratherthan in the depressed regions, in terms of a mass per unit area basis,such that the depressed regions have a significantly lower amount ofhydrophobic matter present than the elevated regions. It is preferredthat the percentage of the hydrophobic material deposited on theelevated regions be at least about 60 percent, more specifically atleast about 70 percent, and still more specifically at least about 80percent of the total amount deposited. The hydrophobic matter cancomprise fine fibers, powders, resins, gels, and other materials,preferably applied with an average superficial basis weight of less than10 gsm, more specifically from about 1 to about 10 gsm. When used as theskin-contacting layer of absorbent articles, said absorbent web servesas an absorbent improvement over nonabsorbent, plastic apertured filmsor other inherently hydrophobic materials. The elevated regions of saidbasesheet preferably comprise between about 5 and about 300 protrusionsper square inch having a height relative to the plane of the basesheet,as measured in the uncalendered state, of about 0.1 mm or greater,preferably about 0.2 mm or greater, more preferably about 0.3 mm orgreater, and most preferably from about 0.25 to about 0.6 mm.

[0032] Definition of Terms and Test Procedures

[0033] In describing the webs of this invention and their fluid-handlingcharacteristics, a number of terms and tests are used which aredescribed below.

[0034] As used herein, “high yield pulp fibers” are those papermakingfibers of pulps produced by pulping processes providing a yield of about65 percent or greater, more specifically about 75 percent or greater,and still more specifically from about 75 to about 95 percent. Yield isthe resulting amount of processed fiber expressed as a percentage of theinitial wood mass. High yield pulps include bleachedchemithermomechanical pulp (BCTMP), chemithermomechanical pulp (CTMP)pressure/pressure thermomechanical pulp (PTMP), thermomechanical pulp(TMP), thermomechanical chemical pulp (TMCP), high yield sulfite pulps,and high yield Kraft pulps, all of which contain fibers having highlevels of lignin. The preferred high yield pulp fibers can also becharacterized by being comprised of comparatively whole, relativelyundamaged fibers, having a freeness of 250 Canadian Standard Freeness(CSF) or greater, more specifically 350 CSF or greater, and still morespecifically 400 CSF or greater, and low fines content (less than 25percent, more specifically less than 20 percent, still more specificallyless that 15 percent, and still more specifically less than 10 percentby the Britt jar test). In addition to common papermaking fibers listedabove, high yield pulp fibers also include other natural fibers such asmilkweed seed floss fibers, abaca, hemp, kenaf, bagasse, cotton and thelike.

[0035] As used herein, “wet resilient pulp fibers” are papermakingfibers selected from the group comprising high-yield fibers, chemicallystiffened fibers and cross-linked fibers. Examples of chemicallystiffened fibers or cross-linked fibers include mercerized fibers, HBAfibers produced by Weyerhaeuser Corp., and those such as described inU.S. Pat. No. 3,224,926, “Method of Forming Cross-linked CellulosicFibers and Product Thereof,” issued in 1965 to L. J. Bernardin, and U.S.Pat. No. 3,455,778, “Creped Tissue Formed From Stiff Cross-linked Fibersand Refined Papermaking Fibers,” issued in 1969 to L. J. Bernardin.Though any blend of wet resilient pulp fibers can be used, high-yieldpulp fibers are the wet resilient fiber of choice for many embodimentsof the present invention for their low cost and good fluid handlingperformance when used according to the principles described below.

[0036] The amount of high-yield or wet resilient pulp fibers in thebasesheet can be at least about 10 dry weight percent or greater, morespecifically about 15 dry weight percent or greater, more specificallyabout 30 dry weight percent or greater, still more specifically about 50dry weight percent or greater, and still more specifically from about 20to 100 percent. For layered basesheets, these same amounts can beapplied to one or more of the individual layers. Because wet resilientpulp fibers are generally less soft than other papermaking fibers, insome applications it is advantageous to incorporate them into the middleof the final product, such as placing them in the center layer of athree-layered basesheet or, in the case of a two-ply product, placingthem in the inwardly-facing layers of each of the two plies.

[0037] “Water retention value” (WRV) is a measure that can be used tocharacterize some fibers useful for purposes of this invention. WRV ismeasured by dispersing 0.5 grams of fibers in deionized water, soakingat least 8 hours, then centrifuging the fibers in a 1.9 inch diametertube with a 100 mesh screen at the bottom of the tube at 1000 G for 20minutes. The samples are weighed, then dried at 105° C. for two hoursand then weighed again. WRV is (wet weight—dry weight)/dry weight. Highyield pulp fibers can have a WRV of about 0.7 or greater andcharacteristically have a WRV of about 1 or greater and preferably fromabout 1 to about 2. Low-yield, cross-linked fibers typically have aWater Retention Value of less than about 1, specifically less than about0.7 and more specifically still less than about 0.6.

[0038] “Rewet” is a measure of the amount of liquid water which can bewicked out of a moistened web into an adjacent dry filter paper and isintended to estimate the tendency of a moistened web to wet the skin.The Rewet test is performed by cutting a sample of a tissue web to arectangle of dimensions 4 in×6 in. The test is performed in a Tappiconditioned room (50% RH, 73° F.). The initial air dry weight of theconditioned sample is recorded, then deionized water is sprayed ontoboth sides of the tissue sample to uniformly wet it, bringing the totalwet mass of the tissue to a value of 4 times the previously recordedinitial air dry weight of the sample, thus bringing the “apparentmoisture ratio” of the sample to a value of 3.0 grams (±0.15 g) of addedwater per gram of conditioned air dry fiber. The process of repeatedlyspraying and weighing the sample until the proper mass has been reachedshould take no more than 2 minutes. Once the sample is wetted, a singledry Whatman #3 filter, whose mass has been measured and recorded, isplaced on the center of the wet tissue sample and a load is immediatelyplaced on the filter disk. The load is a cylindrical disk of aluminumhaving a diameter of 4.5 inches and a thickness of 1 inch for a mass of723 g. The aluminum disk should be centered about the filter disk. Thefilter paper on the wet sample remains under load for 20 seconds, atwhich time the load and the filter paper are immediately removed. Thefilter paper is then weighed, and the additional mass relative to theinitial air dry mass is reported in grams as the Rewet value.

[0039] “Normalized Rewet” is the Rewet value of a sample divided by theconditioned dry mass of the sample.

[0040] “Absorbency at 0.075 psi” is a measure of basesheet absorbentcapacity under a load of 0.075 psi. The test requires two metal platescut to a length of 6 inches and a width of 4 inches. A lower plate is0.125-inches thick and the upper plate is ¾-inch thick aluminum having amass of 813 g, which imparts a load of 0.075 psi when placed flat on atissue sample. The center of the upper plate has a cylindrical hole0.25-inches in diameter. To perform the test, 4-in×6-in samples of drytissue are cut, with the 6-in length being aligned with the machinedirection. Multiple tissue plies are stacked to achieve a tissue stackweight as close to 2.8 grams as possible. The tissue stack is placedbetween the two horizontal plates, which lie flat in a larger tray. Atitrating burette with 50 ml of deionized water is aligned directlyabove the hole in the upper plate. The burette is opened and water isallowed to slowly enter the hole in the upper plate such that the holeis filled with a column of water that is maintained as high as possiblewithout rising above or spilling onto the upper surface of the plate.This is done until the sample is apparently saturated. Apparentsaturation is the point at which water begins to leave any edge of thesample. The mass of water that has been removed from the burette istaken as the value for “Horizontal Absorbency at 0.075 psi.” At thatpoint, the tray containing the plates is tilted at a 45° angle for 30seconds to allow some of the liquid in the sample to drain. The mass ofany liquid that drains out is subtracted from the previous “HorizontalAbsorbency at 0.075 psi” value to yield “Tilted Absorbency at 0.075psi.” For the basesheet, the horizontal absorbency at 0.075 psi can beabout 5 g or greater, or alternatively 7 g or greater, 9 g or greater,11 g or greater, or from about 6 g to about 10 g. The tilted absorbencyat 0.075 psi may be about 4 g or greater, about 6 g or greater, about 8g or greater, about 10 g or greater, or from about 6 to about 10 g. Thetilted absorbency of the cover may be about 5 to 40% less than that offthe basesheet alone, while the horizontal absorbency may be greater orlower than that off the basesheet.

[0041] “Fabric side” of a through-air dried paper web is the side of theweb that was in contact with the through-air dryer fabric (TAD fabric)during through-drying. Typically the fabric side of a through-driedsheet offers the most pleasant tactile properties for contact with skin.

[0042] “Air side” of a through-air dried paper web is the side of theweb that was not in contact with the through-air dryer fabric (TADfabric) during through-drying. Typically the air side of a through-driedsheet feels somewhat more gritty than the fabric side of the same sheet.

[0043] “Density” can be determined by measuring the caliper of a singlesheet using a TMI tester (Testing Machines, Inc., Amityville, N.Y.) witha load of 0.289 psi, e.g., using a TMI Model 49-70 with an enlargedplaten. Density is calculated by dividing the caliper by the basisweight of the sheet. The basesheets useful for the purposes of thisinvention can have low, substantially uniform densities (high bulks),which is preferred for wet laid structures, or may have a distributionof zones of varying density, which is preferred in airlaid basesheets.Substantial density uniformity is attained, for example, bythroughdrying to final dryness without differentially compressing theweb. In general, the density of the basesheets of this invention can beabout 0.3 gram per cubic centimeter (g/cc) or less, more specificallyabout 0.15 g/cc or less, still more specifically about 0.1 g/cc or lessand can be from about 0.05 to 0.3 g/cc or from about 0.07 to 0.2 g/cc.It is desirable that the basesheet structure, once formed, be driedwithout substantially reducing the number of wet-resilient interfiberbonds. Throughdrying, which is a common method for drying tissues andtowels, is a preferred method of preserving the structure. Basesheetsmade by wet laying followed by throughdrying typically have a density ofabout 0.1 gram per cubic centimeter, whereas airlaid basesheets normallyused for diaper fluff typically have densities of about 0.05 gram percubic centimeter. All of such basesheets are within the scope of thisinvention.

[0044] As used herein, “dry bulk” is measured with a thickness gaugehaving a circular platen 3 inches in diameter such that a pressure of0.05 psi is applied to the sample, which should be conditioned at 50%relative humidity and at 73° F. for 24 hours prior to measurement. Thebasesheet as well as the uncalendered web can have a dry bulk of 3 cc/gor greater, preferably 6 cc/g or greater, more preferably 9 cc/g orgreater, more preferably still 11 cc/g or greater, and most preferablybetween 8 cc/g and 28 cc/g.

[0045] “Wet strength agents” are materials used to immobilize the bondsbetween the fibers in the wet state. Typically the means by which fibersare held together in paper and tissue products involve hydrogen bondsand sometimes combinations of hydrogen bonds and covalent and/or ionicbonds. In the present invention, it is desirable to provide a materialthat will allow bonding of fibers in such a way as to immobilize thefiber to fiber bond points and make them resistant to disruption in thewet state. In this instance the wet state usually will mean when theproduct is largely saturated with water or other aqueous solutions, butcould also mean significant saturation with body fluids such as urine,blood, mucus, menses, runny bowel movement, lymph and other bodyexudates.

[0046] There are a number of materials commonly used in the paperindustry to impart wet strength to paper and board that are applicableto this invention. These materials are known in the art as “wet strengthagents” and are commercially available from a wide variety of sources.Any material that when added to a paper web or sheet results inproviding the sheet with a wet geometric tensile strength:dry geometrictensile strength ratio in excess of 0.1 will, for purposes of thisinvention, be termed a wet strength agent. Typically these materials aretermed either as permanent wet strength agents or as “temporary” wetstrength agents. For the purposes of differentiating permanent fromtemporary wet strength, permanent will be defined as those resins which,when incorporated into paper or tissue products, will provide a productthat retains more than 50% of its original wet strength after exposureto water for a period of at least five minutes. Temporary wet strengthagents are those which show less than 50% of their original wet strengthafter being saturated with water for five minutes. Both, classes ofmaterial find application in the present invention. The amount of wetstrength agent added to the pulp fibers can be at least about 0.1 dryweight percent, more specifically about 0.2 dry weight percent orgreater, and still more specifically from about 0.1 to about 3 dryweight percent based on the dry weight of the fibers.

[0047] Permanent wet strength agents will provide a more or lesslong-term wet resilience to the structure. In contrast, the temporarywet strength agents would provide structures that had low density andhigh resilience, but would not provide a structure that had long-termresistance to exposure to water or body fluids. The mechanism by whichthe wet strength is generated has little influence on the products ofthis invention as long as the essential property of generatingwater-resistant bonding at the fiber/fiber bond points is obtained.

[0048] Suitable permanent wet strength agents are typically watersoluble, cationic oligomeric or polymeric resins that are capable ofeither crosslinking with themselves (homocrosslinking) or with thecellulose or other constituent of the wood fiber. The most widely-usedmaterials for this purpose are the class of polymer known aspolyamide-polyamine-epichlorohydrin (PAE) type resins. These materialshave been described in patents issued to Keim (U.S. Pat. Nos. 3,700,623and 3,772,076) and are sold by Hercules, Inc., Wilmington, Del., asKYMENE 557H. Related materials are marketed by Henkel Chemical Co.,Charlotte, N.C. and Georgia-Pacific Resins, Inc., Atlanta, Ga.

[0049] Polyamide-epichlorohydrin resins are also useful as bondingresins in this invention. Materials developed by Monsanto and marketedunder the SANTO RES label are base-activated polyamide-epichlorohydrinresins that can be used in the present invention. These materials aredescribed in patents issued to Petrovich (U.S. Pat. No. 3,885,158; U.S.Pat. No. 3,899,388; U.S. Pat. No. 4,129,528 and U.S. Pat. No. 4,147,586)and van Eenam (U.S. Pat. No. 4,222,921). Although they are not ascommonly used in consumer products, polyethylenimine resins are alsosuitable for immobilizing the bond points in the products of thisinvention. Another class of permanent-type wet strength agents areexemplified by the aminoplast resins obtained by reaction offormaldehyde with melamine or urea.

[0050] Suitable temporary wet strength resins include, but are notlimited to, those resins that have been developed by American Cyanamidand are marketed under the name PAREZ 631 NC (now available from CytecIndustries, West Paterson, N.J.). This and similar resins are describedin U.S. Pat. Nos. 3,556,932 to Coscia et al. and 3,556,933 to Williamset al. Other temporary wet strength agents that should find applicationin this invention include modified starches such as those available fromNational Starch and marketed as CO-BOND 1000. It is believed that theseand related starches are disclosed in U.S. Pat. No. 4,675,394 to Solareket al. Derivatized dialdehyde starches, such as described in JapaneseKokai Tokkyo Koho JP 03,185,197, may also provide temporary wetstrength. It is also expected that other temporary wet strengthmaterials such as those described in U.S. Pat. No. 4,981,557; U.S. Pat.No. 5,008,344 and U.S. Pat. No. 5,085,736 to Bjorkquist would be of usein this invention. With respect to the classes and the types of wetstrength resins listed, it should be understood that this listing issimply to provide examples and that this is neither meant to excludeother types of wet strength resins, nor is it meant to limit the scopeof this invention.

[0051] Although wet strength agents as described above find particularadvantage for use in connection with this invention, other types ofbonding agents can also be used to provide the necessary wet resiliency.They can be applied at the wet end of the basesheet manufacturingprocess or applied by spraying or printing, etc. after the basesheet isformed or after it is dried.

[0052] “Noncompressive drying” refers to drying methods for dryingcellulosic webs that do not involve compressive nips or other stepscausing significant densification or compression of a portion of the webduring the drying process. Such methods include through-air drying; airjet impingement drying; non-contacting drying such as air flotationdrying, as taught by E. V. Bowden, E. V., Appita J., 44(1): 41 (1991);through-flow or impingement of superheated steam; microwave drying andother radiofrequency or dielectric drying methods, water extraction bysupercritical fluids; water extraction by nonaqueous, low surfacetension fluids, infrared drying; drying by contact with a film of moltenmetal; and other methods. It is believed that the three-dimensionalbasesheets of the present invention could be dried with any of the abovementioned noncompressive drying means without causing significant webdensification or a significant loss of their three-dimensional structureand their wet resiliency properties. Standard dry creping technology isviewed as a compressive drying method since the web must be mechanicallypressed onto part of the drying surface, causing significantdensification of the regions pressed onto the heated Yankee cylinder.Technology to noncompressively dewater and dry tissue webs with an airpress and optionally with a Yankee dryer operated without creping isdisclosed in the following commonly owned copending applications: U.S.patent application Ser. No. unknown, “Method of Producing Low DensityResilient Webs” by F. G. Druecke et al., Attorney Docket No. 13,504,filed Oct. 31, 1997; U.S. patent application Ser. No. unknown, “LowDensity Resilient Webs and Methods of Making Such Web” by S. Chen etal., Attorney Docket No. 13,381, filed Oct. 31, 1997; U.S. patentapplication Ser. No. 08/647,508 filed May 14, 1996 by M. A. Hermans etal. titled “Method and Apparatus for Making Soft Tissue;” and U.S.patent application Ser. No. unknown filed Oct. 31, 1997 titled “AirPress for Dewatering a Wet Web” by F. Hada et al., all of which areherein incorporated by reference. Also of potential value for the tissuemaking operations useful in the present invention is the paper machinedisclosed in U.S. Pat. No. 5,230,776 issued Jul. 27, 1993 to I. A.Andersson et al.; and the capillary dewatering techniques disclosed inU.S. Pat. Nos. 5,598,643 issued Feb. 4, 1997 and 4,556,450 issued Dec.3, 1985, both to S. C. Chuang et al., all of which are incorporatedherein by reference. The dewatering concepts disclosed by J. D. Lindsayin “Displacement Dewatering to Maintain Bulk,” Paperija Puu, 74(3):232-242 (1992) are also of potential value.

[0053] As used herein, the “wet:dry ratio” is the ratio of the geometricmean wet tensile strength divided by the geometric mean dry tensilestrength. Geometric mean tensile strength (GMT) is the square root ofthe product of the machine direction tensile strength and thecross-machine direction tensile strength of the web. Unless otherwiseindicated, the term “tensile strength” means “geometric mean tensilestrength.” The basesheets of this invention preferably have a wet:dryratio of about 0.1 or greater, more specifically about 0.15 or greater,more specifically about 0.2 or greater, still more specifically about0.3 or greater, and still more specifically about 0.4 or greater, andstill more specifically from about 0.2 to about 0.6. Tensile strengthscan be measured using an Instron tensile tester using a 3-inch jawwidth, a jaw span of 4 inches, and a crosshead speed of 10 inches perminute after maintaining the sample under TAPPI conditions for 4 hoursbefore testing. For enhanced wet resiliency and integrity, thebasesheets of this invention also preferably have a minimum absoluteratio of dry tensile strength to basis weight of about 1 gram/gsm,preferably from about 2 grams/gsm, more preferably about 5 grams/gsm,more preferably about 10 grams/gsm and still more preferably about 20grams/gsm and preferably from about 15 to 50 grams/gsm.

[0054] “Overall Surface Depth”. A three-dimensional basesheet or web isa sheet with significant variation in surface elevation due to theintrinsic structure of the sheet itself. As used herein, this elevationdifference is expressed as the “Overall Surface Depth.” The basesheetsuseful for this invention possess three-dimensionality and have anOverall Surface Depth of about 0.1 mm. or greater, more specificallyabout 0.3 mm. or greater, still more specifically about 0.4 mm. orgreater, still more specifically about 0.5 mm. or greater, and stillmore specifically from about 0.4 to about 0.8 mm.

[0055] The three-dimensional structure of a largely planar sheet can bedescribed in terms of its surface topography. Rather than presenting anearly flat surface, as is typical of conventional paper, the moldedsheets useful in producing the present invention have significanttopographical structures that, in one embodiment, may derive in partfrom the use of sculptured through-drying fabrics such as those taughtby Chiu et al. in U.S. Pat. No. 5,429,686, previously incorporated byreference. The resulting basesheet surface topography typicallycomprises a regular repeating unit cell that is typically aparallelogram with sides between 2 and 20 mm in length. For wetlaidmaterials, it is preferred that these three-dimensional basesheetstructures be created by molding the moist sheet or be created prior todrying, rather than by creping or embossing or other operations afterthe sheet has been dried. In this manner, the three-dimensionalbasesheet structure is more likely to be well-retained upon wetting,helping to provide high wet resiliency and to promote good in-planepermeability. For air-laid basesheets, the structure may be imparted bythermal embossing of a fibrous mat with binder fibers that are activatedby heat. For example, an air-laid fibrous mat containing thermoplasticor hotmelt binder fibers may be heated and then embossed before thestructure cools to permanently give the sheet a three-dimensionalstructure.

[0056] In addition to the regular geometrical structure imparted by thesculptured fabrics and other fabrics used in creating a basesheet,additional fine structure, with an in-plane length scale less than about1 mm, can be present in the basesheet. Such a fine structure can stemfrom microfolds created during differential velocity transfer of the webfrom one fabric or wire to another prior to drying. Some of thematerials of the present invention, for example, appear to have finestructure with a fine surface depth of 0.1 mm or greater, and sometimes0.2 mm or greater, when height profiles are measured using a commercialmoiré interferometer system. These fine peaks have a typical half-widthless than 1 mm. The fine structure from differential velocity transferand other treatments may be useful in providing additional softness,flexibility, and bulk. Measurement of the surface structures isdescribed below.

[0057] An especially suitable method for measurement of Overall SurfaceDepth is moiré interferometry, which permits accurate measurementwithout deformation of the surface. For reference to the materials ofthe present invention, surface topography should be measured using acomputer-controlled white-light field-shifted moiré interferometer withabout a 38 mm field of view. The principles of a useful implementationof such a system are described in Bieman et al. (L. Bieman, K. Harding,and A. Boehniein, “Absolute Measurement Using Field-Shifted Moiré,” SPIEOptical Conference Proceedings, Vol. 1614, pp. 259-264, 1991). Asuitable commercial instrument for moiré interferometry is the CADEYES®interferometer produced by Medar, Inc. (Farmington Hills, Mich.),constructed for a 38-mm field-of-view (a field of view within the rangeof 37 to 39.5 mm is adequate). The CADEYES® system uses white lightwhich is projected through a grid to project fine black lines onto thesample surface. The surface is viewed through a similar grid, creatingmoiré fringes that are viewed by a CCD camera. Suitable lenses and astepper motor adjust the optical configuration for field shifting (atechnique described below). A video processor sends captured fringeimages to a PC computer for processing, allowing details of surfaceheight to be back-calculated from the fringe patterns viewed by thevideo camera.

[0058] In the CADEYES moiré interferometry system, each pixel in the CCDvideo image is said to belong to a moiré fringe that is associated witha particular height range. The method of field-shifting, as described byBieman et al. (L. Bieman, K. Harding, and A. Boehnlein, “AbsoluteMeasurement Using Field-Shifted Moiré,” SPIE Optical ConferenceProceedings, Vol. 1614, pp. 259-264, 1991) and as originally patented byBoehnlein (U.S. Pat. No. 5,069,548, herein incorporated by reference),is used to identify the fringe number for each point in the video image(indicating which fringe a point belongs to). The fringe number isneeded to determine the absolute height at the measurement pointrelative to a reference plane. A field-shifting technique (sometimestermed phase-shifting in the art) is also used for sub-fringe analysis(accurate determination of the height of the measurement point withinthe height range occupied by its fringe). These field-shifting methodscoupled with a camera-based interferometry approach allows accurate andrapid absolute height measurement, permitting measurement to be made inspite of possible height discontinuities in the surface. The techniqueallows absolute height of each of the roughly 250,000 discrete points(pixels) on the sample surface to be obtained, if suitable optics, videohardware, data acquisition equipment, and software are used thatincorporates the principles of moiré interferometry with field-shifting.Each point measured has a resolution of approximately 15 microns in itsheight measurement.

[0059] The computerized interferometer system is used to acquiretopographical data and then to generate a grayscale image of thetopographical data, said image to be hereinafter called “the heightmap.” The height map is displayed on a computer monitor, typically in256 shades of gray and is quantitatively based on the topographical dataobtained for the sample being measured. The resulting height map for the38-mm square measurement area should contain approximately 250,000 datapoints corresponding to approximately 500 pixels in both the horizontaland vertical directions of the displayed height map. The pixeldimensions of the height map are based on a 512×512 CCD camera whichprovides images of moiré patterns on the sample which can be analyzed bycomputer software. Each pixel in the height map represents a heightmeasurement at the corresponding x- and y-location on the sample. In therecommended system, each pixel has a width of approximately 70 microns,i.e. represents a region on the sample surface about 70 microns long inboth orthogonal in-plane directions). This level of resolution preventssingle fibers projecting above the surface from having a significanteffect on the surface height measurement. The z-direction heightmeasurement must have a nominal accuracy of less than 2 microns and az-direction range of at least 1.5 mm. (For further background on themeasurement method, see the CADEYES Product Guide, Medar, Inc.,Farmington Hills, Mich., 1994, or other CADEYES manuals and publicationsof Medar, Inc.)

[0060] The CADEYES system can measure up to 8 moiré fringes, with eachfringe being divided into 256 depth counts (sub-fringe heightincrements, the smallest resolvable height difference). There will be2048 height counts over the measurement range. This determines the totalz-direction range, which is approximately 3 mm in the 38-mmfield-of-view instrument. If the height variation in the field of viewcovers more than eight fringes, a wrap-around effect occurs, in whichthe ninth fringe is labeled as if it were the first fringe and the tenthfringe is labeled as the second, etc. In other words, the measuredheight will be shifted by 2048 depth counts. Accurate measurement islimited to the main field of 8 fringes.

[0061] The moiré interferometer system, once installed and factorycalibrated to provide the accuracy and z-direction range stated above,can provide accurate topographical data for materials such as papertowels (Those skilled in the art may confirm the accuracy of factorycalibration by performing measurements on surfaces with knowndimensions.) Tests are performed in a room under Tappi conditions (73°F., 50% relative humidity). The sample must be placed flat on a surfacelying aligned or nearly aligned with the measurement plane of theinstrument and should be at such a height that both the lowest andhighest regions of interest are within the measurement region of theinstrument.

[0062] Once properly placed, data acquisition is initiated using Medar'sPC software and a height map of 250,000 data points is acquired anddisplayed, typically within 30 seconds from the time data acquisitionwas initiated. (Using the CADEYES® system, the “contrast thresholdlevel” for noise rejection is set to 1, providing some noise rejectionwithout excessive rejection of data points.) Data reduction and displayare achieved using CADEYES® software for PCs, which incorporates acustomizable interface based on Microsoft Visual Basic Professional forWindows (version 3.0). The Visual Basic interface allows users to addcustom analysis tools.

[0063] The height map of the topographical data can then be used bythose skilled in the art to identify characteristic unit cell structures(in the case of structures created by fabric patterns; these aretypically parallelograms arranged like tiles to cover a largertwo-dimensional area) and to measure the typical peak to valley depth ofsuch structures. A simple method of doing this is to extracttwo-dimensional height profiles from lines drawn on the topographicalheight map which pass through the highest and lowest areas of the unitcells. These height profiles can then be analyzed for the peak to valleydistance, if the profiles are taken from a sheet or portion of the sheetthat was lying relatively flat when measured. To eliminate the effect ofoccasional optical noise and possible outliers, the highest 10% and thelowest 10% of the profile should be excluded, and the height range ofthe remaining points is taken as the surface depth. Technically, theprocedure requires calculating the variable which we term “P10,” definedat the height difference between the 10% and 90% material lines, withthe concept of material lines being well known in the art, as explainedby L. Mummery, in Surface Texture Analysis: The Handbook, HommelwerkeGmbH, Mühlhausen, Germany, 1990. In this approach, which will beillustrated with respect to FIG. 7, the surface 31 is viewed as atransition from air 32 to material 33. For a given profile 30, takenfrom a flat-lying sheet, the greatest height at which the surfacebegins—the height of the highest peak—is the elevation of the “0%reference line” 34 or the “0% material line,” meaning that 0% of thelength of the horizontal line at that height is occupied by material.Along the horizontal line passing through the lowest point of theprofile, 100% of the line is occupied by material, making that line the“100% material line” 35. In between the 0% and 100% material lines(between the maximum and minimum points of the profile), the fraction ofhorizontal line length occupied by material will increase monotonicallyas the line elevation is decreased. The material ratio curve 36 givesthe relationship between material fraction along a horizontal linepassing through the profile and the height of the line. The materialratio curve is also the cumulative height distribution of a profile. (Amore accurate term might be “material fraction curve.”)

[0064] Once the material ratio curve is established, one can use it todefine a characteristic peak height of the profile. The P10 “typicalpeak-to-valley height” parameter is defined as the difference 37 betweenthe heights of the 10% material line 38 and the 90% material line 39.This parameter is relatively robust in that outliers or unusualexcursions from the typical profile structure have little influence onthe P10 height. The units of P10 are mm. The Overall Surface Depth of amaterial is reported as the P10 surface depth value for profile linesencompassing the height extremes of the typical unit cell of thatsurface. “Fine surface depth” is the P10 value for a profile taken alonga plateau region of the surface which is relatively uniform in heightrelative to profiles encompassing a maxima and minima of the unit cells.Measurements are reported for the most textured side of the basesheetsof the present invention, which is typically the side that was incontact with the through-drying fabric when air flow is toward thethrough-dryer. FIG. 8 represents a profile of Example 13 of the presentinvention, discussed below, having an Overall Surface Depth of about0.5.

[0065] Overall Surface Depth is intended to examine the topographyproduced in the basesheet, especially those features created in thesheet prior to and during drying processes, but is intended to exclude“artificially” created large-scale topography from dry convertingoperations such as embossing, perforating, pleating, etc. Therefore, theprofiles examined should be taken from unembossed regions if thebasesheet has been embossed, or should be measured on an unembossedbasesheet. Overall Surface Depth measurements should exclude large-scalestructures such as pleats or folds which do not reflect thethree-dimensional nature of the original basesheet itself. It isrecognized that sheet topography may be reduced by calendering and otheroperations which affect the entire basesheet. Overall Surface Depthmeasurement can be appropriately performed on a calendered basesheet.

[0066] The “Wet Wrinkle Recovery Test” is a slight modification of AATCCTest Method 66-1990 taken from the Technical Manual of the AmericanAssociation of Textile Chemists and Colorists (1992), page 99. Themodification is to first wet the samples before carrying out the method.This is done by soaking the samples in water containing 0.01 percentTRITON X-100 wetting agent (Rohm & Haas) for five minutes beforetesting. Sample preparation is carried out at 73° F. and 50 percentrelative humidity. The sample is gently removed from the water with atweezers, drained by pressing between two pieces of blotter paper with325 grams of weight, and placed in the sample holder to be tested aswith the dry wrinkle recovery test method. The test measures the highestrecovery angle of the sample being tested (in any direction, includingthe machine direction and the cross-machine direction), with 180°representing total recovery. The Wet Wrinkle Recovery, expressed as apercent recovery, is the measured recovery angle divided by 180°,multiplied by 100. Basesheets of this invention can exhibit a WetWrinkle Recovery of about 60 percent or greater, more specifically about70 percent or greater, and still more specifically about 80 percent orgreater.

[0067] “Wet compressive resiliency” of the basesheets is defined byseveral parameters and can be demonstrated using a materials propertyprocedure that encompasses both wet and dry characteristics. Aprogrammable strength measurement device is used in compression mode toimpart a specified series of compression cycles to an initially dry,conditioned sample, after which the sample is carefully moistened in aspecified manner and subjected to the same sequence of compressioncycles. While the comparison of wet and dry properties is of generalinterest, the most important information from this test concerns the wetproperties. The initial testing of the dry sample can be viewed as aconditioning step. The test sequence begins with compression of the drysample to 0.025 psi to obtain an initial thickness (cycle A), then tworepetitions of loading up to 2 psi followed by unloading (cycles B andC). Finally, the sample is again compressed to 0.025 psi to obtain afinal thickness (cycle D). (Details of the procedure, includingcompression speeds, are given below). Following the treatment of the drysample, moisture is applied uniformly to the sample using a fine mist ofdeionized water to bring the moisture ratio (g water/g dry fiber) toapproximately 1.1. This is done by applying 95-110% added moisture,based on the conditioned sample mass. This puts typical cellulosicmaterials in a moisture range where physical properties are relativelyinsensitive to moisture content (e.g., the sensitivity is much less thanit is for moisture ratios less than 70%). The moistened sample is thenplaced in the test device and the compression cycles are repeated.

[0068] Three measures of wet resiliency are considered which arerelatively insensitive to the number of sample layers used in the stack.The first measure is the bulk of the wet sample at 2 psi. This isreferred to as the “Wet Compressed Bulk” (WCB). The second measure istermed “Wet Springback Ratio” (WS), which is the ratio of the moistsample thickness at 0.025 psi at the end of the compression test (cycleD) to the thickness of the moist sample at 0.025 psi measured at thebeginning of the test (cycle A). The third measure is the “LoadingEnergy Ratio” (LER), which is the ratio of loading energy in the secondcompression to 2 psi (cycle C) to that of the first compression to 2 psi(cycle B) during the sequence described above, for a wetted sample. Thefinal wet bulk measured at the end of the test (at 0.025 psi) is termedthe “final bulk” or “FB” value. When load is plotted as a function ofthickness, loading energy is the area under the curve as the sample goesfrom an unloaded state to the peak load of that cycle. For a purelyelastic material, the springback and loading energy ratio would beunity. Applicants have found that the three measures described here arerelatively independent of the number of layers in the stack and serve asuseful measures of wet resiliency. Also referred to herein is the“Compression Ratio”, which is defined as the ratio of moistened samplethickness at peak load in the first compression cycle to 2 psi to theinitial moistened thickness at 0.025 psi.

[0069] In carrying out the foregoing measurements of the wet compressiveresiliency, samples should be conditioned for at least 24 hours underTAPPI conditions (50% RH, 73° F.). Specimens are die cut to 2.5″×2.5″squares. Conditioned sample weight should be near 0.4 g, if possible,and within the range of 0.25 to 0.6 g for meaningful comparisons. Thetarget mass of 0.4 g is achieved by using a stack of 2 or more sheets ifthe sheet basis weight is less than 65 gsm. For example, for nominal 30gsm sheets, a stack of 3 sheets will generally be near 0.4 g total mass.

[0070] Compression measurements are performed using an Instron 4502Universal Testing Machine interfaced with a 286 PC computer runningInstron Series XIl software (1989 issue) and Version 2 firmware. Thestandard “286 computer” referred to has an 80286 processor with a 12 MHzclock speed. The particular computer used was a Compaq DeskPro 286e withan 80287 math coprocessor and a VGA video adapter. A 1 kN load cell isused with 2.25″ diameter circular platens for sample compression. Thelower platen has a ball bearing assembly to allow exact alignment of theplatens. The lower platen is locked in place while under load (30-100lbf) by the upper platen to ensure parallel surfaces. The upper platenmust also be locked in place with the standard ring nut to eliminateplay in the upper platen as load is applied.

[0071] Following at least one hour of warm-up after start-up, theinstrument control panel is used to set the extensionometer to zerodistance while the platens are in contact (at a load of 10-30 lb). Withthe upper platen freely suspended, the calibrated load cell is balancedto give a zero reading. The extensionometer and load cell should beperiodically checked to prevent baseline drift (shirting of the zeropoints). Measurements must be performed in a controlled humidity andtemperature environment, according to TAPPI specifications (50%±2% RHand 73° F.). The upper platen is then raised to a height of 0.2 in. andcontrol of the Instron is transferred to the computer.

[0072] Using the Instron Series XII Cyclic Test software with a 286computer, an instrument sequence is established with 7 markers (discreteevents) composed of 3 cyclic blocks (instructions sets) in the followingorder:

[0073] Marker 1: Block 1

[0074] Marker 2: Block 2

[0075] Marker 3: Block 3

[0076] Marker 4: Block 2

[0077] Marker 5: Block 3

[0078] Marker 6: Block 1

[0079] Marker 7: Block 3.

[0080] Block 1 instructs the crosshead to descend at 1.5 in./min. untila load of 0.1 lb. is applied (the Instron setting is −0.1 lb., sincecompression is defined as negative force). Control is by displacement.When the targeted load is reached, the applied load is reduced to zero.

[0081] Block 2 directs that the crosshead range from an applied load of0.05 lb. to a peak of 8 lb. then back to 0.05 lb. at a speed of 0.4in./min. Using the Instron software, the control mode is displacement,the limit type is load, the first level is −0.05 lb., the second levelis −8 lb., the dwell time is 0 sec., and the number of transitions is 2(compression, then relaxation); “no action” is specified for the end ofthe block.

[0082] Block 3 uses displacement control and limit type to simply raisethe crosshead to 0.2 in. at a speed of 4 in./min., with 0 dwell time.Other Instron software settings are 0 in first level, 0.2 in secondlevel, 1 transition, and “no action” at the end of the block.

[0083] When executed in the order given above (Markers 1-7), the Instronsequence compresses the sample to 0.025 psi (0.1 lbf), relaxes, thencompresses to 2 psi (8 lbs.), followed by decompression and a crossheadrise to 0.2 in., then compress the sample again to 2 psi, relaxes, liftsthe crosshead to 0.2 in., compresses again to 0.025 psi (0.1 lbf), andthen raises the crosshead. Data logging should be performed at intervalsno greater than every 0.02″ or 0.4 lb. (whichever comes first) for Block2 and for intervals no greater than 0.01 lb. for Block 1. Preferably,data logging is performed every 0.004 lb. in Block 1 and every 0.05 lb.or 0.005 in. (whichever comes first) in Block 2.

[0084] The results output of the Series XII software is set to provideextension (thickness) at peak loads for Markers 1, 2, 4 and 6 (at each0.025 and 2.0 psi peak load), the loading energy for Markers 2 and 4(the two compressions to 2.0 psi previously termed cycles B and C,respectively), the ratio of the two loading energies (second cycle/firstcycle), and the ratio of final thickness to initial thickness (ratio ofthickness at last to first 0.025 psi compression). Load versus thicknessresults are plotted on the screen during execution of Blocks 1 and 2.

[0085] In performing a measurement, the dry, conditioned sample iscentered on the lower platen and the test is initiated. Followingcompletion of the sequence, the sample is immediately removed andmoisture (deionized water at 72-73° F.) is applied. Moisture is applieduniformly with a fine mist to reach a moist sample mass of approximately2.0 times the initial sample mass (95-110% added moisture is applied,preferably 100% added moisture, based on conditioned sample mass; thislevel of moisture should yield an absolute moisture ratio of about 1.1g. water/g. oven dry fiber—with oven dry referring to drying for atleast 30 minutes in an oven at 105° C.). (For the uncreped throughdriedmaterials of this invention, the moisture ratio could be within therange of 1.05 to 1.7 without significantly affecting the results). Themist should be applied uniformly to separated sheets (for stacks of morethan 1 sheet), with spray applied to both front and back of each sheetto ensure uniform moisture application. This can be achieved using aconventional plastic spray bottle, with a container or other barrierblocking most of the spray, allowing only about the upper 10-20% of thespray envelope—a fine mist—to approach the sample. The spray sourceshould be at least 10″ away from the sample during spray application. Ingeneral, care must be applied to ensure that the sample is uniformlymoistened by a fine spray. The sample must be weighed several timesduring the process of applying moisture to reach the targeted moisturecontent. No more than three minutes should elapse between the completionof the compression test on the dry sample and the completion of moistureapplication. Allow 45-60 seconds from the final application of spray tothe beginning of the subsequent compression test to provide time forinternal wicking and absorption of the spray. Between three and fourminutes will elapse between the completion of the dry compressionsequence and initiation of the wet compression sequence.

[0086] Once the desired mass range has been reached, as indicated by adigital balance, the sample is centered on the lower Instron platen andthe test sequence is initiated. Following the measurement, the sample isplaced in a 105° C. oven for drying, and the oven dry weight will berecorded later (sample should be allowed to dry for 30-60 minutes, afterwhich the dry weight is measured).

[0087] Note that creep recovery can occur between the two compressioncycles to 2 psi, so the time between the cycles may be important. Forthe instrument settings used in these Instron tests, there is a 30second period (±4 sec.) between the beginning of compression during thetwo cycles to 2 psi. The beginning of compression is defined as thepoint at which the load cell reading exceeds 0.03 lb. Likewise, there isa 5-8 second interval between the beginning of compression in the firstthickness measurement (ramp to 0.025 psi) and the beginning of thesubsequent compression cycle to 2 psi. The interval between thebeginning of the second compression cycle to 2 psi and the beginning ofcompression for the final thickness measurement is approximately 20seconds.

[0088] The utility of a web or absorbent structure having a high WetCompressed Bulk (WCB) value is obvious, for a wet material which canmaintain high bulk under compression can maintain higher fluid capacityand is less likely to allow fluid to be squeezed out when it iscompressed.

[0089] High Wet Springback Ratio values are especially desirable becausea wet material that springs back after compression can maintain highpore volume for effective intake and distribution of subsequent insultsof fluid, and such a material can regain fluid during its expansionwhich may have been expelled during compression. In diapers, forexample, a wet region may be momentarily compressed by body motion orchanges in body position. If the material is unable to regain its bulkwhen the compressive force is released, its effectiveness for handlingfluid is reduced.

[0090] High Loading Energy Ratio values in a material are also useful,for such a material continues to resist compression (LER is based on ameasure of the energy required to compress a sample) at loads less thanthe peak load of 2 psi, even after it has been heavily compressed once.Maintaining such wet elastic properties is believed to contribute to thefeel of the material when used in absorbent articles, and may helpmaintain the fit of the absorbent article against the wearer's body, inaddition to the general advantages accrued when a structure can maintainits pore volume when wet.

[0091] The hydrophobically-treated absorbent webs of this invention andthe untreated, inherently hydrophilic basesheets useful in producingthis invention can exhibit one or more of the foregoing properties. Morespecifically, said absorbent webs and basesheets can have a WetCompressed Bulk of about 6 cubic centimeters per gram or greater, morespecifically about 7 cubic centimeters per gram or greater, morespecifically about 8 cubic centimeters per gram or greater, and stillmore specifically from about 8 to about 13 cubic centimeters per gram.The Compression Ratio can be about 0.7 or less, more specifically about0.6 or less, still more specifically about 0.5 or less, and still morespecifically from 0.4 to about 0.7. Also, they can have a Wet SpringbackRatio of about 0.6 or greater, more specifically about 0.7 or greater,more specifically about 0.85, and still more specifically from about 0.8to about 0.93. The Loading Energy Ratio can be about 0.6 or greater,more specifically 0.7 or greater, more specifically still about 0.8 orgreater, and most specifically from about 0.75 to about 0.9. Final bulkcan be about 8 cubic centimeters per gram or greater or preferably about12 centimeters per gram or greater.

[0092] “In-Plane Permeability”. An important property of porous media,particularly for absorbent products, is the permeability to liquid flow.The complex, interconnected pathways between the solid particles andboundaries of a porous media provide routes for fluid flow which mayoffer significant flow resistance due to the narrowness of the channelsand the tortuosity of the pathways.

[0093] For paper, permeability is commonly expressed in terms of gasflow rates through a sheet. This practice is useful for comparingsimilar sheets, but does not truly characterize the interaction offlowing fluid with the porous structure and provides no directinformation about flow in a wet sheet. The standard engineeringdefinition of permeability provides a more useful parameter, though oneless easily measured. The standard definition is based on Darcy's law(see F. A. L. Dullien, Porous Media: Fluid Transport and Pore Structure,Academic Press, New York, 1979), which, for one-dimensional flow, statesthat the velocity of fluid flow through a saturated porous medium isdirectly proportional to the pressure gradient: $\begin{matrix}{V = {\frac{K}{\mu}\Delta \quad \frac{P}{L}}} & (1)\end{matrix}$

[0094] where V is the superficial velocity (flow rate divided by area),K is the permeability, μ is the fluid viscosity, and ΔP is the pressuredrop in the flow direction across a distance L. The units of K are m².In Equation (1), the permeability is an empirical proportionalityparameter linking fluid velocity to pressure drop and viscosity. For ahomogeneous medium, K is not a function of ΔP, sample length, orviscosity, but is an intrinsic parameter describing the flow resistanceof the medium. In a compressible medium, permeability will be a functionof the degree of compression. Darcian permeability is a fundamentalparameter for processes involving fluid flow in fibrous webs.

[0095] Darcian permeability has units of area (m²) and for simpleuniform cylindrical pores is proportional to the cross sectional area ofa single pore. However, the permeability of most real materials cannotbe predicted from an optical assessment of pore size. Permeability isdetermined not only by pore size, but also pore orientation, tortuosity,and interconnectedness. Large pores in the body of an object may beinaccessible to fluid flow or accessible only through minute poresoffering high flow resistance. Even with a full three-dimensionaldescription of the pore space of a material from x-ray tomography orother imaging techniques, it is difficult to predict or calculate thepermeability. Permeability and pore size determinations are related butdistinct pieces of information about a material. For example, a sheet ofmetal with discreet, nonoverlapping holes punched in it may have verylarge pores (the holes), while still having negligible In-PlanePermeability. Swiss cheese has many large pores, but typically hasnegligible permeability in any direction unless sliced so thin thatindividual holes can extend from one face to the other of the cheesesample.

[0096] Most studies of permeability in paper have focused on flow in thez-direction (normal to the plane of the sheet), which is of practicalimportance in wet pressing and other unit operations. However, paper isan anisotropic material (for example, see E. L. Back, “The PoreAnisotropy of Paper Products and Fibre Building Boards,” SvenskPapperstidning, 69: 219 (1966)), meaning that fluid flow properties area function of direction. In this case, different flow directions willappear to have different apparent permeabilities. The many possibilitiesof flow direction and pressure gradients in such a medium can beencompassed with a multidimensional form of Darcy's law, $\begin{matrix}{{\overset{\_}{v} = \frac{{- \overset{=}{K}} \cdot {\nabla P}}{\mu}},} & (2)\end{matrix}$

[0097] where {overscore (v)} is the superficial velocity vector(volumetric flow rate divided by cross-sectional area of the flow), μ isthe viscosity of the fluid, {double overscore (K)} is a second-ordertensor and ∇P is the pressure gradient. If a Cartesian coordinate systemis chosen to correspond with the principal flow directions of the porousmedium, then the permeability tensor becomes a diagonal matrix (seeJacob Bear, “Dynamics of Fluids in Porous Media.,” American Elsevier,New York, N.Y., 1972, pp. 136-151): $\begin{matrix}{{\overset{=}{K} = \begin{bmatrix}K_{x} & 0 & 0 \\0 & K_{y} & 0 \\0 & 0 & K_{z}\end{bmatrix}},} & (3)\end{matrix}$

[0098] where K_(x), K_(y), and K_(z) are the principal permeabilitycomponents in the x-, y-, and z-directions, respectively. In paper,these directions will generally correspond to the cross-direction (takenhere as y) and the machine-direction (taken as x, the direction ofmaximum In-Plane Permeability) in the plane, and the transverse orthickness direction (z). Thus, the anisotropic permeability of typicalmachine-made paper can be characterized with three permeabilityparameters, one for the machine-direction, one for the cross-direction,and one for the z-direction. (In some cases, as when there areunbalanced flows in the headbox of the paper machine, the direction ofmaximum permeability may be slightly off from the machine direction; thedirection of maximum In-Plane Permeability and the direction orthogonalto that should be used for the x- and y-directions, respectively, inthat case.) In handsheets, there may be no preferential direction oforientation for fibers lying in the plane, so the x- and y-directionpermeability values should be equal (in other words, such a sheet isisotropic in the plane).

[0099] In spite of the past focus on z-direction permeability in paper,In-Plane Permeability (both K_(x) and K_(y) are in-plane factors) isimportant in a variety of applications, especially in absorbentarticles. Body fluids or other liquids flowing into the absorbentarticle usually enter the article in a narrow, localized region.Efficient use of the absorbent medium requires that the incoming fluidbe distributed laterally through in-plane flow in the absorbent article,otherwise the local capacity of the article to handle the incomingliquid may be overwhelmed resulting in leakage and poor utilization ofthe absorbent core. The ability of fluid to flow in the plane of thearticle is a function of the driving force for fluid flow, which can bea combination of capillary wicking and hydraulic pressure from fluidsource, and of the ability of the porous medium to conduct flow, whichis described in large part by the Darcian permeability of the material.Two-phase flow and non-Newtonian liquids or suspensions complicate thephysics, but the in-plane permeability of the porous medium is acritical factor for rapid in-plane distribution of liquid insults.Especially in the case of urine management, where liquid flow rates mayoccur far in excess of the ability of capillary forces, high In-PlanePermeability is needed in the intake layer to allow the fluid to bedistributed laterally rather than to leak.

[0100] While many past studies of liquid permeability in paper focusedexclusively on measuring K_(z) for z-direction flow, more recently,methods have been taught for measuring permeability in the plane of apaper sheet. J. D. Lindsay and P. H. Brady teach methods for in-planeand z-direction permeability measurements of saturated paper in “Studiesof Anisotropic Permeability with Applications to Water Removal inFibrous Webs: Part I,” Tappi J., 76(9): 119-127 (1993) and “Studies ofAnisotropic Permeability with Applications to Water Removal in FibrousWebs: Part II,” Tappi J., 76(11): 167-174 (1993). Related methods havebeen published by K. L. Adams, B. Miller, and L. Rebenfeld in “ForcedIn-Plane Flow of an Epoxy Resin in Fibrous Networks,” PolymerEngineering and Science, 26(20) 1434-1441 (1986); J. D. Lindsay in“Relative Flow Porosity in Fibrous Media: Measurements and Analysis,Including Dispersion Effects,” Tappi J., 77(6): 225-239 (June 1994); JD. Lindsay and J. R. Wallin, “Characterization of In-Plane Flow inPaper,” AlChE 1989 and 1990 Forest Products Symposium, Tappi Press,Atlanta, Ga. (1992), p. 121; and D. H. Horstmann, J. D. Lindsay, and R.A. Stratton, “Using Edge-Flow Tests to Examine the In-Plane AnisotropicPermeability of Paper,” Tappi J., 74(4): 241 (1991).

[0101] The basic method used in most of these publications is injectionof fluid into the center of a paper disk that is constrained between twoflat surfaces to force the fluid flow to be in the radial direction,proceeding from the injection point at the center of the disk to theouter edge of the disk. This is illustrated in FIG. 9, which depicts asheet 41 in which a central hole 42 has been punched and into whichfluid is injected by means of an injection port of the same size as thepunched hole. Fluid is forced to flow to the outer radial edge 43. For aliquid-saturated sheet of constant thickness subject to steady radialfluid flow in the manner described in the work of Lindsay and others,the equation relating average In-Plane Permeability to fluid flow is:$\begin{matrix}{{{K_{r} \equiv \frac{K_{x} + K_{y}}{2}} = \frac{Q\quad \mu \quad {\ln \left( {R_{o}/R_{i}} \right)}}{2\quad \pi \quad L_{p}\Delta \quad P}},} & (4)\end{matrix}$

[0102] where R_(o) is the radius of the paper disk 41, R_(i) is theradius of the central hole 42 in the sample into which fluid is injectedthrough an injection port; L_(p) is the thickness of the paper; ΔP isthe constant pressure above atmospheric pressure at which fluid isinjected into the disk (the gauge pressure at the injection pore); Q isthe volumetric flow rate of liquid, and K_(r) is the In-PlanePermeability, technically the average radial permeability, defined asthe average of the two in-plane permeability components. The diskdiameter is 5 inches. The central inlet hole 42 was consistently 0.375inches (⅜ inch) and was created using a paper punch tool The testapparatus for In-Plane Permeability measurements is depicted in FIG. 10and FIG. 11, which is similar in principle to the apparatus taught byLindsay and Brady, previously cited. Tubing 45 connects water from awater reservoir to an injection port drilled into a 1-inch thickPlexiglas support plate 45. (The support plate is transparent to permitviewing of the wetted sample, especially in cases when an aqueous dyesolution is injected into the sample. A mirror at a 45 degree anglebelow the support plate facilitates viewing and photography.) The waterreservoir 51 provides a nearly constant hydraulic head 49 for fluidinjection during the test. The volumetric flow rate is obtained bynoting the change in water reservoir mass as a function of time, andconverting the water mass flow rate to a volumetric flow rate.Vacuum-deaerated deionized water at room temperature is used.

[0103] In using the apparatus, a paper disk 41, cut to be 5-inches indiameter and having a central hole diameter of 0.375-inches, is placedon the support plate 46 over the injection port 44 (0.375 inchesdiameter also) and is then saturated with water. The fluid injectionline 45 and the injection port 44 should be filled with water andefforts should be taken to avoid air bubbles being trapped in the sheetor in the injection area. To help eliminate air pockets, the sample 41should be bent gently in the center as it is placed on the wet supportplate to initiate liquid contact in the center of the sample; the edgescan then be lowered gradually to create a wedge-like motion of theliquid meniscus to sweep air bubbles out from under the sheet. Multi-plystacks of sheets can be handled in the same way, although preliminarysample wetting may be needed to remove interply air bubbles. The goal inremoving air bubbles is to reduce the flow blockage that trapped airbubbles can cause.

[0104] Once the wetted sample is in place, a cylindrical metal platen47, 5-inches in diameter, is gently lowered on top of the sample toprovide a constant compressive load and to provide a reference surfaceon its top for thickness measurement with displacement gauges 48. Threedisplacement gauges 48 are used, spaced approximately evenly around theedge of the top of the metal cylinder 47, in order to measure theaverage thickness of the sheet 41. The sample thickness is taken as theaverage of the three displacement values relative to a zero point whenno sample is present. A suitable thickness gauge is the MitutoyoDigimatic Indicator, Model 543-525-1, with a 2-inch stroke (travelingdistance of the contacting spindle) and a precision of 1 micrometer. Thethickness gauges are rigidly mounted relative to the support plate. Thecontacting spindles of the thickness gauges can be raised and lowered(without changing the position of the body of the gauge) by use of acable to provide clearance for moving the metal platen onto the sample.The small force applied by the thickness gauges 48 should be added tothe weight of the metal platen 47 to obtain the total force applied tothe sample 41; this force, when divided by the cross sectional area ofthe sample and platen, should be 0.8 psi.

[0105] A hydraulic head of 13 inches is used to drive the liquid flow.The head is the vertical distance 49 between the water line 50 of thesupply reservoir 51 and the plane of the sample 41. This head isachieved by placement of a water bottle 51, filled to a specified level50, on a mass balance 52 at a fixed height relative to the support plate46 on which the sample rests. As the sample is being placed on thesupport plate, the water reservoir is at such a height that the waterlevel 50 in the reservoir is nearly the same as (or slightly greaterthan) the support plate 46 on which the sample rests. When the samplehas been moistened and placed under the compressive load of the metalplaten, the water reservoir is then raised and placed on a mass balance52 such that the water level is 13 inches above the support platen. Atimer is activated and the water reservoir mass is recorded at 20seconds or 30 seconds intervals for a least 90 seconds. The thicknessreadings of the three gauges is also recorded regularly during the test.To reduce creep, the saturated sample should be allowed to equilibrateunder the compressive load for at least 30 seconds before the waterbottle is raised and forced flow through the sample begins.

[0106] The change in water reservoir mass as a function of time givesthe mass flow rate, which can easily be converted to a volumetric flowrate for use in Equation 4. Normal engineering principles should be usedto ensure that the proper units (preferably SI units) are used inapplying Equation 4.

[0107] In performing In-Plane Permeability measurements, it is importantthat the sample be uniformly compressed against the restraining surfacesto prevent large channels or openings that would provide paths of leastresistance for substantial liquid flow that could bypass much of thesample itself. Ideally, the liquid will flow uniformly through thesample, and this can be ascertained by injecting dyed fluid into thesample and observing the shape of the dyed region through thetransparent support plate. Injected dye should spread out uniformly fromthe injection point. In isotropic samples, the shape of the moving dyeregion should be nearly circular. In materials with in-plane anisotropydue to fiber orientation or small-scale structural orientation, theshape of the dye region should be oval or elliptical, and nearlysymmetric about the injection point. A suitable dye for such tests isVersatint Purple II made by Milliken Chemical Corp. (Inman, S.C.). Thisis a fugitive dye that does not absorb onto cellulose, allowing for easyvisualization of liquid flow through the fibrous medium.

[0108] As will be illustrated in the Examples, the webs and basesheetsof this invention possess very high In-Plane Permeability. The In-PlanePermeability can be about 0.1×10⁻¹⁰ square meters or greater, morespecifically about 0.3×10⁻¹⁰ square meters or greater, more specificallyabout 0.5×10⁻¹⁰ square meters or greater, still more specifically fromabout 0.5×10⁻¹⁰ to about 8×10⁻¹⁰ square meters, and still morespecifically from about 0.8×10⁻¹⁰ to about 5×10⁻¹⁰ square meters.

BRIEF DESCRIPTION OF THE DRAWINGS

[0109]FIG. 1 is a cross-section of an absorbent web comprising acontoured, resilient basesheet having zones of hydrophobic material.

[0110]FIG. 2 depicts the absorbent web of FIG. 1 in contact with anunderlying absorbent fibrous layer.

[0111]FIG. 3 depicts the absorbent web of FIG. 1 attached to an invertedbasesheet having similar topography.

[0112]FIG. 4 depicts a paper machine suitable for producing thecontoured, resilient basesheet of the present invention shown in FIG. 1.

[0113]FIG. 5 depicts a version of FIG. 2 in which the low regions of thebasesheet are provided with apertures.

[0114]FIG. 6 depicts a pattern of hydrophobic material printed onto ahydrophilic basesheet.

[0115]FIG. 7 depicts a height profile and several material lines toillustrate the definition of material surface curve and the P10 height.

[0116]FIG. 8 depicts a CADEYES profile from Sample 13 of the presentinvention.

[0117]FIG. 9 portrays the flow pattern in a paper disk during anIn-Plane Permeability measurement (angle view).

[0118]FIG. 10 is a side view of the In-Plane Permeability apparatus.

[0119]FIG. 11 is a top view of the brass platen and thickness gauges inthe In-Plane Permeability apparatus.

[0120]FIG. 12 depicts the grayscale height map of a section of uncrepedtissue basesheet showing relatively high regions as light gray and lowerregions as darker gray or black.

[0121]FIG. 13 is a graph of mean Rewet values and 95% confidenceintervals for samples of Example 1.

[0122]FIG. 14 is a table of physical property results for Examples 3-6.

[0123]FIG. 15 is a table of physical property results for Examples 7-10.

BRIEF DESCRIPTION OF THE DRAWINGS

[0124]FIG. 1 shows a cross section of a contoured, inherentlyhydrophilic basesheet 1, preferably a resilient cellulosic tissue sheet,onto which hydrophobic material 2 has been deposited on the uppermostregions 3 of the contoured basesheet to form a composite absorbent web.The upper side of the web having the hydrophobic material 2 can serve asthe skin-contacting layer of a topsheet or liner in an absorbentarticle. The hydrophobic material preferably resides only on theelevated regions of the basesheet as shown, preferably penetrating intono more than about 50% of the thickness of the basesheet, morespecifically no more than about 20% of the thickness of the basesheet,and most preferably no more than about 10% of the thickness of thebasesheet. For some products, it may be desirable that the hydrophobicmaterial lie almost exclusively on the upper (outer) surface of thefibers on the upper surface of the basesheet, with very littlepenetration into the basesheet itself. The hydrophobic material depositsgenerally have a thickness that rises some distance above the underlyinghydrophilic basesheet. In some embodiments, the distance above theunderlying hydrophilic basesheet can be less than 3 mm, less than 0.5mm, less than 0.1 mm, less than 0.05 mm, or between 0.05 and 0.5 mm. Insome preferred embodiments, the thickness of the hydrophobic depositsrelative to the local thickness of the hydrophilic basesheet can be lessthan 50%, alternatively less than about 20%, alternatively less thanabout 10%, or between about 5% and 25%.

[0125] For best performance in terms of liquid absorption, the densityof the basesheet preferably should be substantially uniform throughoutany characteristic cross-section of the basesheet, as is characteristicof uncreped, through-air dried tissues and other paper sheets that havebeen dried by largely noncompressive means. Such a basesheet isrelatively free of regions having low permeability and low absorbentcapacity and tends to be more resilient when wet. The depressed regions4 of the basesheet are substantially hydrophilic and can serve much asapertures do in an apertured film by providing pore space to receiveliquids and by providing regions in the midst of hydrophobic materialwhere liquid can be wicked into an absorbent medium, the medium beingthe hydrophilic basesheet itself and optionally an underlying absorbentcore preferably in liquid communicating contact with the composite web.The underlying absorbent core is preferably a fibrous mat such as a matof fluff pulp. One such embodiment is depicted in FIG. 2, where theinherently hydrophilic basesheet 1 is in direct contact with a fibrousmat 5. For enhanced transport of liquid out of the composite web intothe fibrous mat, the fibrous mat 5 may be provided with a heterogeneousstructure having high density regions with small pores to provide highcapillary pressure to pull liquid out of the composite web, while stillhaving a significant amount of low density regions to provide adequatepore space to hold large quantities of fluid and to provide highpermeability regions. A heterogeneously densified fibrous mat 5 can havea relatively dense upper layer in contact with the basesheet 1, or itcan have a pattern of densified regions imparted by embossing or othermeans, preferably with at least some of the densified regions in directcontact with the lower hydrophilic portions 4 of the basesheet 1.

[0126] As shown in FIG. 3, the inherently hydrophilic basesheet 1 canalso be in contact 9 with a web of similar topography having depressions7 to form a multi-ply structure with significant interply pore space 8.Preferably, the web provides a combination of desired materialproperties: wet resiliency, to maintain shape and bulk when wet;absorbency and good capillary structure to provide rapid intake of fluidin the hydrophilic areas, softness on the upper surface on the body sidefor improved comfort; flexibility for comfort during use; and athree-dimensional contour to reduce contact area against the body, thusresulting in less of a wet feel when wet.

[0127] The inherently hydrophilic basesheet can be produced by a widevariety of methods. Preferably, the basesheet, prior to any calenderingthat may be desired, is characterized by a low-density three-dimensionalstructure created in substantial part before the sheet reaches a solidslevel (dryness level) of about 60% or higher and preferably about 70% orhigher. Suitable low-density three-dimensional structures can beachieved by a variety of means known in the arts of papermaking, tissueproduction, and nonwoven web production, including but not limited tothe use of specially treated high-bulk fibers such as curled orchemically treated fibers as an additive in the furnish, including thefibers taught by C. C. Van Haaften in “Sanitary Napkin with Cross-linkedCellulosic Layer,” U.S. Pat. No. 3,339,550, issued Sep. 5, 1967, whichis hereby incorporated by reference; mechanical debonding means such asdifferential velocity (“rush”) transfer between fabrics or wires,hereafter described; mechanical straining or “wet straining” of themoist web, including the methods taught by M. A. Hermans et al. in U.S.Pat. No. 5,492,598, “Method for Increasing the Internal Bulk ofThroughdried Tissue,” issued Feb. 20, 1996, herein incorporated byreference, and M A Hermans et al. in U.S. Pat. No 5,411,636, “Method forIncreasing the Internal Bulk of Wet-Pressed Tissue,” issued May 2, 1995,herein incorporated by reference; molding of the fiber onto athree-dimensional wire or fabric, such as the fabrics disclosed by Chiuet al. in U.S. Pat. No. 5,429,686, “Apparatus for Making Soft TissueProducts,” issued Jul. 4, 1995, which is hereby incorporated byreference, including differential velocity transfer onto or from saidthree-dimensional wire or fabric; wet embossing of the sheet;hydroentanglement of fibers; wet creping; and the optional use ofchemical debonding agents. Inherently hydrophilic basesheets may also beproduced from composites of synthetics and pulp fibers, with oneembodiment disclosed in commonly owned U.S. Pat. No. 5,389,202, “Processfor Making a High Pulp Content Nonwoven Composite Fabric,” issued Feb.14, 1995 to Cherie H. Everhart et al., hereby incorporated by reference.

[0128] Air laid mixtures of cellulosic and synthetic fibers are withinthe scope of the present invention. Pulp fibers for air laying may beprepared by comminution, as by a hammermill, or other means known in theart. Methods of forming air laid materials are well known in the art,including, for example, the methods disclosed by Dunning and Day in U.S.Pat. No. 3,976,734, issued Aug. 24, 1976, and U.S. Pat. No. 5,156,902,issued Oct. 20, 1992 to Pieper et al., both of which are hereinincorporated by reference. Suitable papermaking fibers for air layingmay include hardwood or softwood, low or high yield fibers, andchemically treated fibers such as mercerized pulps, chemically stiffenedor crosslinked fibers, sulfonated fibers, and the like. Useful fiberpreparation methods include those of Hermans et al. disclosed in U.S.Pat. No. 5,501,768, issued Mar. 26, 1996, and U.S. Pat. No. 5,348,620,issued Sep. 20, 1994, both of which are herein incorporated byreference. Fiber softening methods known in the art may also beemployed, including the compounds disclosed by Smith et al. in U.S. Pat.No. 5,552,020, issued Sep. 3, 1996, herein incorporated by reference.The pulp fibers may be entrained in air or steam and combined orcommingled with newly formed, hot synthetic fibers from a meltblown orspunbond process, or the pulp fibers may be mixed with a stream ofrelatively short, cut synthetic fibers (preferably less than 22 mm inlength) entrained in air. Bonding agents and adhesives may be used toimpart stability and wet strength to the air laid structure, or heat maybe applied to partially melt some of the synthetic fibers to providebonding. One embodiment comprises mixtures of papermaking fibers andmeltblown polymers known as “coform” as taught in U.S. Pat. No.4,100,324 issued to Anderson et al.; U.S. Pat. No. 4,879,170 issued toRadwanski et al.; and U.S. Pat. No. 4,931,355 issued to Radwanski etal., all herein incorporated by reference. For the purposes of thisinvention, steps should be taken to impart appropriate texture to theweb. Such steps may include forming on a screen having a pattern of lowand high permeabilities to produce a web of patterned basis weight andthickness, spot bonding, pattern bonding, embossing, pulling out regionsof the web in the z-direction to disrupt the surface in a predeterminedpattern, ultrasonic pattern bonding, web disruption with hydraulic jetsof liquid, and so forth. Desirably, inherently hydrophobic syntheticfibers may be treated to increase wettability with respect to water,urine or menses, using methods such as surfactant coating, supercriticalfluid deposition of surfactants or other surface active agents on thefiber surface, deposition of protein or amphiphilic protein, coronadischarge treatment, ozonation, coating with hydrophilic matter, and thelike. When synthetic fibers are used in the production of the basesheet,they may constitute 70% or less by weight of the basesheet, preferably40% or less, more preferably 20% or less, more preferably still 10% orless, and most preferably between about 1% and about 10%. Alternatively,the web may comprise between about 1% and about 10% synthetic fibers.Alternatively, the web may comprise between about 1% and 50% ofsynthetic polymer fibers. A lower content of synthetic fiber isgenerally desirable to reduce cost, although other factors may be moreimportant in determining the optimum fiber mix for a specific product.Other suitable materials for incorporation in absorbent articles of thepresent invention include the soft webs of Tanzer et al. in U.S. Pat.No. 5,562,645, issued Oct. 8, 1996, herein incorporated by reference.

[0129] In a preferred embodiment, the basesheet is a wet-laid tissueproduced without creping and dried by non-compressive means. Techniquesfor producing such sheets are disclosed by S. J. Sudall and S. A. Engelin U.S. Pat. No. 5,399,412, “Uncreped Throughdried Towels and WipersHaving High Strength and Absorbency,” issued Mar. 21, 1995; R. F. Cookand D. S. Westbrook in U.S. Pat. No. 5,048,589, “Non-creped Hand orWiper Towel,” issued Sep. 17, 1991; and J. S. Rugowski et al.,“Papermaking Machine for Making Uncreped Throughdried Tissue Sheets,”U.S. Pat. No. 5,591,309, Jan. 7, 1997; all herein incorporated byreference.

[0130] A preferred method for producing the basesheet for the presentinvention is depicted in FIG. 4. For simplicity, the various tensioningrolls schematically used to define the several fabric runs are shown butnot numbered. It will be appreciated that variations from the apparatusand method illustrated in FIG. 4 can be made without departing from thescope of the invention. Shown is a twin wire former having a layeredpapermaking headbox 10 which injects or deposits a stream 11 of anaqueous suspension of papermaking fibers onto the forming fabric 13which serves to support and carry the newly-formed wet web downstream inthe process as the web is partially dewatered to a consistency of about10 dry weight percent. Additional dewatering of the wet web can becarried out, such as by vacuum suction. while the wet web is supportedby the forming fabric. The headbox 10 may be a conventional headbox ormay be a stratified headbox capable of producing a multilayered unitaryweb. For example, it may be desirable to provide relatively short orstraight fibers in one layer of the basesheet to give a layer with highcapillary pressure, while the other layer comprises relatively longer,bulkier, or more curled fibers for high permeability and high absorbentcapacity and high pore volume. It may also be desirable to applydifferent chemical agents to separate layers of a single web to optimizedry and wet strength, pore space, wetting angle, appearance, or otherproperties of a web. Multiple headboxes may also be used to create alayered structure, as is known in the art.

[0131] The wet web is transferred from the forming fabric to a transferfabric 17 preferably traveling at a slower speed than the forming fabricin order to impart increased stretch into the web. This is commonlyreferred to as “rush” transfer. One useful means of performing rushtransfer is taught in U.S. Pat. No. 5,667,636, issued Mar. 4, 1997 to S.A. Engel et al., herein incorporated by reference. The relative speeddifference between the two fabrics can be from 0-80 percent, preferablygreater than 10%, more preferably from about 10 to 60 percent, and mostpreferably from about 10 to 40 percent. Transfer is preferably carriedout with the assistance of a vacuum shoe 18 such that the forming fabricand the transfer fabric simultaneously converge and diverge at theleading edge of the vacuum slot.

[0132] The web is then transferred from the transfer fabric to thethroughdrying fabric 19 with the aid of a vacuum transfer roll 20 or avacuum transfer shoe, optionally again using a fixed gap transfer aspreviously described. The throughdrying fabric can be traveling at aboutthe same speed or a different speed relative to the transfer fabric. Ifdesired, the throughdrying fabric can be run at a slower speed tofurther enhance stretch. Transfer is preferably carried out with vacuumassistance to ensure deformation of the sheet to conform to thethroughdrying fabric, thus yielding desired bulk and appearance.Suitable throughdrying fabrics are described in U.S. Pat. No. 5,429,686issued to Kai Chiu et al., previously incorporated by reference.

[0133] In a preferred embodiment, the fabric comprises a sculpture layersuperposed on or integrally connected to a load bearing layer, saidsculpture layer comprising elongated, raised elements having an aspectratio of at least 4, preferably at least 6, more preferably at least 10,more preferably still at least 20, and most preferably between about 8and about 50. The fabric may be woven or nonwoven. In one embodiment,the fabric is a woven fabric wherein the load bearing layer comprisesinterwoven machine-direction warps and cross-direction chutes and thesculpture layer comprises additional warps or chutes interwoven in theweave of the load bearing layer, wherein the highest knuckles of thesculpture layer may be higher than the highest knuckles of the loadbearing layer by about 0.1 mm or greater, preferably 0.2 mm or greater,more preferably 0.5 mm or greater, and most preferably between about 0.4mm and about 2 mm. For purposes of imparting improved cross-directionstretch of the basesheet, the elongated, raised elements of thesculpture layer should be preferentially oriented in the machinedirection.

[0134] The number of elongated, raised elements per square inch of thefabric should be between about 5 and about 300, more preferably betweenabout 10 and about 100. The resulting throughdried basesheet will haveelevated regions preferably comprising between about 5 and about 300protrusions per square inch having a height relative to the plane of thebasesheet, as measured in the uncalendered state and uncreped state, ofabout 0.1 mm or greater, preferably 0.2 mm or greater, more preferablyabout 0.3 mm or greater, and most preferably from about 0.25 to about0.6 mm. When the basesheet structure comprises a relatively planarportion with both protrusions and depressions departing therefrom, therelatively planar portion is taken as the plane of the basesheet. Insome structures, a basesheet plane may not be well defined. In suchcases, the protrusion height can be measured relative to thecharacteristic depth of the deepest depressions. In any case, theprotrusion height relative to the characteristic depth of the deepestdepressions, as measured in the uncalendered state and uncreped state,can be about 0.1 mm or greater, preferably 0.3 mm or greater, morepreferably about 0.4 mm or greater, more preferably still about 0.5 mmor greater, and most preferably from about 0.4 to about 1.2 mm. In onespecific embodiment, the elevated regions of the basesheet correspond toelevated machine-direction knuckles from a sculpture layer of athree-dimensional throughdrying fabric used to produce an uncrepedthroughdried web. Webs formed in this manner have unusually high valuesof cross-direction stretch prior to failure, as measured in standardtensile tests, of 6% or greater, preferably 9% or greater, and morepreferably 12% or greater, due to the high cross-direction topographyimparted by the elevated machine-direction elements on a throughdryingfabric. The machine direction stretch can be enhanced by rush transferand can be at least as great as the cross-direction stretch andpreferably at least 10% and more preferably at least 14%

[0135] The level of vacuum used for the web transfers can be from about3 to about 15 inches of mercury (75 to about 380 millimeters ofmercury), preferably about 5 inches (125 millimeters) of mercury. Thevacuum shoe (negative pressure) can be supplemented or replaced by theuse of positive pressure from the opposite side of the web to blow theweb onto the next fabric in addition to or as a replacement for suckingit onto the next fabric with vacuum. Also, a vacuum roll or rolls can beused to replace the vacuum shoe(s).

[0136] While supported by the throughdrying fabric, the web is finaldried to a consistency of about 94 percent or greater by thethroughdryer 21 and thereafter transferred to a carrier fabric 22. Thedried basesheet 23 is transported to the reel 24 using carrier fabric 22and an optional carrier fabric 25. An optional pressurized turning roll26 can be used to facilitate transfer of the web from carrier fabric 22to fabric 25. Suitable carrier fabrics for this purpose are AlbanyInternational 84M or 94M and Asten 959 or 937, all of which arerelatively smooth fabrics having a fine pattern. Although not shown,reel calendering or subsequent off-line calendering can be used toimprove the smoothness and softness of the basesheet.

[0137] The basesheet may be slitted, perforated, or provided withapertures formed by cutting, stamping, or the piercing action of finewater jets. Such perforations or apertures may assist in the transfer offluid into an underlying absorbent core. Preferably, the apertures areprovided near or within depressed areas of the contoured basesheet thatserve as hydrophilic zones. FIG. 5 depicts a cross-section of one suchembodiment in which the basesheet 1 has been provided with perforations27 in the low, hydrophilic regions.

[0138] Co-aperturing of the nonwoven material with the underlyingbasesheet, wherein the nonwoven web and the basesheet are simultaneouslyapertured as with pin aperturing of a two-layer structure, is possiblewithin the scope of the present invention but is not preferred.Co-aperturing tends to place hydrophobic matter from the nonwoven webover the hydrophilic matter of the basesheet in the apertures, such thatfluid entering the aperturing might encounter a hydrophobic barrierbetween it and the basesheet. It is desired that fluid entering theapertures be able to flow into the basesheet. Apertures in the basesheetmay enhance subsequent transport into the underlying core, but thehydrophobic properties of the basesheet should contribute positively tothe fluid handling performance of the composite cover material.

[0139] FIGS. 7 to 11 have been previously discussed.

[0140]FIG. 12 shows a representative portion of a grayscale height mapof a basesheet structure of potential value in the present invention,acquired by the CADEYES moiré interferometer (Medar, Inc. FarmingtonHills, Mich.) having a 38-mm field of view. The tissue is an uncrepedthrough-air dried structure having a surface depth of about 0.3 mm.Preferably, the basesheet is textured or molded prior to complete dryingto impart an Overall Surface Depth in the dried structure of about 0.1mm. or greater, more preferably about 0.3 mm. or greater, still morepreferably about 0.4 mm. or greater, still more preferably about 0.5 mm.or greater, and most preferably from about 0.4 to about 0.8 mm. Inanother preferred embodiment, the basesheet further contains at least10% by weight of high yield or other wet resilient pulp fibers and aneffective amount of wet strength resin such that the wet:dry tensileratio is at least about 0.1. The uppermost, elevated regions of thebasesheet preferably offer relatively smooth and flat plateaus in orderto be placed against skin with relatively little sense of grittiness orabrasion.

[0141] The hydrophobic material 2 on the basesheet as shown in FIG. 1 ispreferably deposited on relatively elevated regions of the web, such asthe light gray or white regions on the height map of FIG. 12, in orderto place hydrophobic regions in contact with the user's body when theweb is used as a topsheet in an absorbent article. The hydrophobicmaterial is preferably deposited over a large enough portion of thebasesheet to render a distinct improvement in dry feel while stillallowing liquid transport by wicking in the z-direction (thicknessdirection, normal to the plane of the web) in multiple hydrophilicregions. The proper application of hydrophobic matter to a fraction ofthe upper surface of the hydrophilic basesheet will generally result ina decrease of Rewet value relative to the untreated basesheet (meaningan improvement in the dry feel) of at least about 10%, more specificallyat least about 20%, more specifically at least about 30%, still morespecifically at least about 40%, and most specifically from about 10% toabout 50%. The resulting Rewet value is preferably less than about 1 g,more specifically less than about 0.65 g, more specifically less thanabout 0.5 g, still more specifically less than about 0.4 g, and mostspecifically less than about 0.3 g. The resulting Normalized Rewet valueis preferably less than about 1, more specifically less than about 0.7,more specifically less than about 0.5, still more specifically less thanabout 0.4, and most specifically less than about 0.3. In one embodiment,there is essentially no hydrophobic matter present below the 50%material line of a characteristic profile of the web, or below themidplane of a typical cross section of contoured web.

[0142] In one embodiment, the hydrophobic matter is applied in a mannerdesigned to limit lateral (in-plane) wicking of liquids to preventseepage or leakage from the edges of an absorbent article while alsoimproving the dry feel. Producing this embodiment normally requires thathydrophobic material or materials be added to the upper surface of thehydrophilic basesheet in two ways such that some of the hydrophobicmatter penetrates substantially into the basesheet to establish abarrier region to inhibit in-plane wicking, while the remainder of thehydrophobic matter is applied more lightly to avoid substantialpenetration into the basesheet. The barrier regions may also usehydrophobic matter to fill in the depressions of the web to prevent flowof liquid along surface channels or pores. Different hydrophobicmaterials and application means may be used for the two or more regionsof differing penetration depth or differing basis weight of application.One approach suitable for use in absorbent articles such as femininepads or incontinence pads is to apply longitudinal bands of ahydrophobic material in liquid form, such as a melted wax or polymericcompound, applied heavily enough to permeate into the basesheet for asignificant portion of the thickness of the basesheet. with said bandsbeing near the edges of the absorbent article to limit seepage from theedge. The remaining portion of the basesheet may be treated withhydrophobic matter applied more superficially to be less penetrating.

[0143] Suitable hydrophobic materials may comprise compounds which aresolid or highly viscous at room temperature but become liquid orsignificantly less viscous at elevated temperature, enabling applicationof the liquid at elevated temperature by gravure printing, spray, brushapplication, or other means, whereupon the liquid solidifies, gels, orbecomes substantially immobile at room temperature or body temperature.The hydrophobic agent may also be dissolved, dispersed, or emulsified ina liquid carrier, such as water, and applied to the web by means such ascoating, spraying, or printing, whereafter part of the liquid carrier isremoved by evaporation, sorption, or other means to leave a hydrophobiccoating or impregnation on the web. The hydrophobic agent may alsocomprise solid particles such as PTFE, polyolefins, or other polymersthat have been ground and formulated into a viscous grease or paste.Additionally, the hydrophobic matter may be in solid form, such asfibers or particles that are attached adhesively to the basesheet orattached by entanglement, hydroentanglement, electrostatic attraction,and so forth.

[0144] Suitable hydrophobic materials include silicone compounds,fluorocarbons, PTFE, waxes, wax emulsions, polyurethane emulsions, fatsand fatty acid derivatives, polyolefins, nylon, polyesters, glycerides,and the like, as well as mixtures of the same. Several suitablematerials containing solidified mixtures of waxes and oils are disclosedin commonly owned U.S. Pat. No. 5,601,871, “Soft Treated UncrepedThroughdried Tissue,” issued Feb. 11, 1997 to D. Krzysik et al., hereinincorporated by reference. Disclosed therein are compounds containingoil, wax, and optionally fatty alcohols, said compositions havingmelting points between about 30° C. to about 70° C. When distributedrelatively uniformly over an uncreped tissue, said compositionssignificantly reduce liquid intake rates and reduce friction against theskin. It is believed that the hydrophobic compositions disclosed byKrzysik et al. could also be used advantageously in the presentinvention through a macroscopically nonuniform application of saidcompositions to a portion of the most elevated regions of athree-dimensional, resilient, hydrophilic basesheet in such a manner asto avoid significant reduction of liquid intake rates.

[0145] As disclosed by Krzysik et al., suitable oils include, but arenot limited to, the following classes of oils: petroleum or mineraloils, such as mineral oil and petrolatum; animal oils, such as mink oiland lanolin oil; plant oils, such as aloe extract, sunflower oil, andavocado oil; and silicone oils, such as dimethicone and alkylmethylsilicones. Suitable waxes include, but are not limited to the followingclasses: natural waxes, such as beeswax and carnauba wax; petroleumwaxes, such as paraffin and ceresine wax; silicone waxes, such as alkylmethyl siloxanes; or synthetic waxes, such as synthetic beeswax andsynthetic sperm wax. Useful silicone compounds and methods ofapplication are known in the art, including those of Kasprzak in U.S.Pat. No. 5,302,382, issued Apr. 12, 1994, and Kaun in U.S. Pat. No.5,591,306, issued Jan. 7, 1997, both of which are herein incorporated byreference.

[0146] The amount of fatty alcohol, if present, in the compositions ofKrzysik et al. can include those having a carbon chain length ofC₁₄-C₃₀, including cetyl alcohol, stearyl alcohol, behenyl alcohol, anddodecyl alcohol.

[0147] For some embodiments of the present invention, it is desired thatthe hydrophobic material have a melting point well above typical bodytemperatures since absorbent articles containing the web of the presentinvention may be worn against the body under hot conditions, and anymelting of the hydrophobic material may interfere with the performanceof the absorbent article and eliminate the advantage of a dry feel. Forsuch articles containing the compositions of Krzysik et al. and othercompositions, said compositions should have a melting point above about35° C., specifically above 40° C., more specifically above about 45° C.,and more specifically still above 50° C.

[0148] Other suitable hydrophobic compositions comprise up to 30 weightpercent oil and from about 50 to about 100 weight percent wax, saidcompositions having a melting point of from about 40° C. to about 200°C., more specifically from 70° C. to about 160° C., more specificallyabove 75° C., and more specifically still from about 85° C. to 140° C.For purposes herein, “melting point” is the temperature at which themajority of the melting occurs, it being recognized that meltingactually occurs over a range of temperatures. Hydrophobic materials mayalso be used which do not melt or which degrade or decompose prior to orduring melting.

[0149] Examples of water repellent agents which are potentially usefulin the present invention include polyurethane emulsions such as Aerotex96B of American Cyanamid; fluorochemical agents such as FC 838, FC 826,and the SCOTCHGARD compounds sold by Minnesota Mining and Manufacturingand Milease F-14 and Milease F-31X, sold by ICI. Also desirable are highmolecular weight cationic fluorocarbons which can be formed into aqueousemulsions for ease of application and handling. An example of apotentially useful wax emulsion is Phobotex, sold by Ciba. A variety ofother water-repellent materials that can be applied to paper webs arereviewed and disclosed in U.S. Pat. No. 5,491,190, issued Feb. 13, 1996to Paul E. Sandvick and Calvin J. Verbrugge, incorporated herein byreference. Sandvick and Verbrugge focus primarily on the use of mixturesof fatty acids and polymers for repulpable paper sheets. Various wax andpolymer compositions of potential value for the present invention aredisclosed in U.S. Pat. No. 3,629,171 to Kremer et al.; U.S. Pat. No.3,417,040 to Kremer; U.S. Pat. No. 3,287,149 to Dooley et al.; U.S. Pat.No. 3,165,485 to Ilnyckyj et al.; and U.S. Pat. No. 2,391,621 to Powell,et al., all of which are herein incorporated by reference. Mixtures ofhydrophobic latex and wax may also be used, including those taught inU.S. Pat. No. 4,117,199 to Gotoh et al., herein incorporated byreference. British Pat. No. 1,593,331 to Vase teaches a method fortreating paper and paperboard to make them water resistant by coatingthem with an aqueous latex coating composition. The latex coatingcomposition is an acrylic polymer and a metal stearate or wax where thewax is at least 20% by weight of the total acrylic polymer and metalstearate present. The metal stearate is preferably calcium stearate.Latex emulsions, latex foams, and water absorbing polymers may be used,including those disclosed in U.S. Pat. No. 5,011,864, issued Apr. 30,1991 to Nielsen and Kim, herein incorporated by reference, which alsodiscloses combinations containing chitosan. Potentially useful latexesalso include those disclosed by Stanislawczyk in U.S. Pat. No.4,929,495, and the anionic latex compounds are disclosed in U.S. Pat.No. 4,445,970, issued May 1, 1984, both of which are herein incorporatedby reference. After application, the coating is dried or cured on thepaper. For the present invention, the composition would be appliednonuniformly to the upper surface of a basesheet.

[0150] Other examples of aqueous emulsions and emulsifiable compositionsfor coating paper and the like are found in U.S. Pat. No. 3,020,178 toSweeney et al. and U.S. Pat. No. 3,520,842 to Crean (aqueous mixtures ofpetroleum wax, a polymeric olefin material and a fatty acid are added towater containing an amine soap-forming agent such as an alkanolamine,followed by agitation and homogenization to form an aqueous emulsioncoating composition). The hydrophobic matter may also compriseformulations intended to promote skin wellness and comfort. For example,the hydrophobic matter may include a hydrophobic base such as mineraloil, waxes, petrolatum, cocoa butter, and the like, combined witheffective amounts of skin wellness additives or pharmaceutical agentssuch as antibiotics and or anti-bacterial agents, anti-fungal agents,Vitamin E (alpha tocopherol), lanolin, silicone compounds suitable forskin care, cortisone, zinc oxide, baking soda, corn silk derivatives,avocado oil, emu oil, other natural plant and animal oils, and the like.

[0151] Hydrophobic material may also be applied in fibrous orparticulate form and attached to the basesheet through thermal fusion,chemical binding through the use of a binder agent or adhesive,preferably a water-repellent binder, entanglement (resulting from highvelocity impact against a porous web), electrostatic attachment, and thelike. In a preferred embodiment, the hydrophobic material, whetherapplied as fibers, as particles, or as a liquid or slurry, may becontiguously deposited to form an interconnected network, such as thenetwork of lines shown in FIG. 6, in which case the hydrophilic regionsare isolated from one another. In addition to materials previouslydescribed, useful particulate hydrophobic agents include talcum powderand lycopodium powder.

[0152] Preferably, the hydrophobic material is applied to the desiredregions with an area-averaged local dry basis weight in the range offrom about 0.5 to about 50 gsm, more specifically in the range of fromabout 1 to about 10 gsm, more specifically about 5 gsm or less, and mostspecifically about 3 gsm or less. The hydrophobic matter preferablycomprises about 30% or less of the total mass of the dry absorbent web,more specifically about 20% or less, more specifically about 10% orless, and most specifically from about 1% to about 15% of the total massof the dry absorbent web. The basis weight of the underlying basesheetcan be from about 10 to about 200 gsm, more specifically from about 15to about 70 gsm, and most specifically from about 15 to about 40 gsm.For multi-ply tissue structures, it is preferred that the basis weightbe less than about 40 gsm and more specifically less than about 30 gsm.

[0153] In addition to hydrophobic matter, other agents may be suitablyadded to the basesheet in accordance with this invention, includingsuperabsorbent particles or fibers. Superabsorbent material may bedeposited or attached in the depressed regions of the upper surface ofthe basesheet, or preferably may be incorporated within the fibrousstructure of the basesheet, attached to the lower surface of thebasesheet, or incorporated between the basesheet and an attachedabsorbent core. Other chemical agents may be added to either surface orboth surfaces, or dispersed throughout the basesheet, applied to inneror outer layers of the basesheet, or applied to selected surface regionsof the basesheet, including application in a regular pattern as bygravure printing. Such chemical agents include emollients, lotions,chemical softeners, opacifiers, optical brighteners, wet strengthagents, quaternary ammonium salts, proteins, crosslinking agents,virucides, bactericides, perfumes, dyes, chemical debonders,plasticizers for high yield fibers, zeolites or other agents for odorcontrol, and the like. Chitosan and related derivatives may beincorporated in the articles of the present invention for theiranti-bacterial or other health benefits; triclosan and otheranti-bacterial agents may likewise be incorporated.

[0154] Various mechanical and physical treatments may be applied to thebasesheet before or after addition of hydrophobic material to improvethe mechanical properties, softness, or functionality of the web. Suchtreatments include brushing, differential velocity transfer betweenbelts or fabrics, penetration by high velocity air jets, needling,hydroentanglement, calendering, soft nip calendering, thermal gradientcalendering, corona discharge treatment, electret formation,microstraining, dry creping, embossing, slitting, and aperturing.Preferably, the basesheet is not co-apertured with the topsheet.

[0155] Also within the scope of the present invention are absorbent websin which both sides of the web have been treated with hydrophobicmaterial. Such an embodiment may be useful for absorbent towels andother materials where absorption may occur on either surface. In thatcase, it is preferred that hydrophobic material be placed on the mostelevated regions of both surfaces, the elevated regions being thehighest regions when the respective surface is facing up. Since thedepressions on the upper surface will generally correspond to elevatedregions on the lower surface when the lower surface is facing up,especially when the web has substantially uniform thickness throughoutits cross section, the hydrophobic material on one surface willgenerally not be superposed directly over other hydrophobic material onthe other surface but the hydrophobic regions on the two surfaces willtend to be in a staggered relationship to each other. The type ofhydrophobic material, its method of application, and the amount appliedmay differ on both sides. Likewise, multiple applications of differenthydrophobic materials may be performed on a single surface to achievedesired properties or a desired visual appearance, including the use ofmutlicolored fiber patches, colored adhesives, and the like.

[0156] The scope of the present invention also includes multi-plybasesheet structures and laminates with one or more layers being thedual-zoned absorbent webs described above. For example, the traditionalfluff pulp absorbent core used in many absorbent articles may bereplaced by a series of resilient basesheet layers, such as the wetresilient uncreped, through-air dried basesheets described in Examples7-10 below, and a dual-zoned absorbent web containing hydrophobicmaterial could be placed in superposed relation on said series ofresilient basesheet layers. All or some of the multiple plies may befurther provided with apertures, slits, embossments, and the like.Multiple plies may be fixedly attached to each other through adhesives,sewn thread, entanglement by needling or fluid jets, embossing, and thelike.

[0157] An excellent hand towel can be made by taking advantage of theunusually high wet resiliency of uncreped, non-compressively driedbasesheets, especially those containing resilient fibers such ashigh-yield fibers and containing wet strength agents. The fiber-fiberbonds of such sheets comprise hydrogen and covalent bonds which areformed during non-compressive drying while the sheet is in a molded,three-dimensional structure. While calendering may flatten such abasesheet, many of the bonds are undisturbed. When the basesheet islater wetted, the swelling fibers can be relieved of the stressesimparted by calendering and can return to the structure achieved duringdrying. In a sense, the bonds have locked in a memory of the basesheetstructure achieved during drying and curing of wet strength resins. Thusit is possible to prepare a calendered, flat basesheet which can returnto a bulkier, three-dimensional state upon wetting, as disclosed incommonly owned copending application Ser. No. 60/013,308 filed Mar. 8,1996 to D. Hollenberg et al., herein incorporated by reference. Such a“thin when dry, thick when wet” material can be used advantageously inthe present invention. By adding hydrophobic material to the elevatedregions of a basesheet and then calendering the basesheet, oralternatively, by adding hydrophobic material to the previously-highspots after calendering, a relatively thin, flat absorbent web isproduced which has hydrophilic and hydrophobic regions in essentiallythe same plane. That structure can absorb fluids well upon contactbecause hydrophilic regions are in contact with the fluid. However,after wetting, the absorbent web expands such that the wet-feeling,hydrophilic regions are no longer in direct contact with the skin whilethe dry-feeling, hydrophobic regions become elevated to contact theskin. Such an absorbent web desirably has an Overall Surface Depth ofabout 0.2 mm or less while dry and about 0.3 mm or greater when wettedto a moisture content of 100%. Alternatively, the calendered absorbentweb can have an Overall Surface Depth of about 0.3 mm or less while dryand about 0.4 mm or greater, more specifically about 0.5 mm or greater,when wetted to a moisture content of 100%.

Embodiments with Hydrophobic Fibers

[0158]FIG. 13. depicts a form of a preferred set of embodiments whereinthe hydrophobic material comprises groups or tufts of thin polyolefinfibers 50 or other hydrophobic fibers in order to provide a soft,clothlike feel. The fibers may comprise a variety of fiber lengths andtypes 50 a and 50 b, or may be primarily short fibers 50 c with a fiberlength smaller than the characteristic length of the elevated regions ofthe basesheet or may be primarily long fibers 50 c with a length near orgreater than the characteristic length of the elevated regions of thebasesheet. In one embodiment, the tufts may be patches of shortsynthetic fibers attached preferentially to the elevated regions of theupper surface of the basesheet such that less than 80%, preferably lessthan 50%, and more preferably less than about 25% of the surface area ofsaid basesheet is covered by the attached synthetic fibers. Such fibersmay be applied by adhesives, thermal bonding, ultrasonic binding,electrostatic attraction, needling, entanglement, hydroentanglement orthrough the use of adhesives or binders, including water-repellentbinders. The adhesives or binders may include hydrophilic agents such aspolyvinyl alcohol, starch, cationic latexes, proteins, and the like,provided that the hydrophobic effect of the adhered fibers is notdestroyed or severely reduced by the use of such adhesives. To ensurehydrophobic activity, water-repellent binders may be desirable,including materials such as polybutyl acrylate, styrene-acryliccopolymer, acrylic vinyl chloride copolymer, ethylene-acrylic acidcopolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl chloridecopolymer, acrylic copolymer latex, styrene-butadiene latex, and vinylchloride latex. Suitable repellent binders which may be utilized areGeon 580X83 and Geon 580X119, sold by Goodrich (consisting ofvinylchloride latex); Emulsion E1497, and Emulsion El 847, sold by Rohm& Haas (consisting of an acrylic emulsion); and Rhoplex NW-1285, sold byRohm & Haas (consisting of an acrylic emulsion); Airflex 120 and AirflexEVLC 453, sold by Air Products (consisting of ethylene vinyl chlorideemulsions); Nacrylic 78-3990, sold by National Starch (consisting of anacrylic emulsion) and Primacor, sold by Dow Chemical (consisting of anethylene/acrylic acid copolymer).

[0159] As shown in FIG. 13, a densified absorbent material 51 preferablyis in contact with the lower side of the hydrophilic basesheet 1 whereinthe densified absorbent material has a pore size smaller than thecharacteristic pore size of the basesheet 1 or a density greater thanthe density of the basesheet 1 and preferably has a density of about 0.1g/cc or less, and more preferably about 0.2 g/cc or less. The densifiedabsorbent material can be an airlaid web or a densified fluff pulp layeror other layers of cellulosic tissue. Preferably the densified absorbentmaterial is stabilized to prevent excessive expansion or loss ofabsorbent capacity upon wetting. Stabilization can be achieved throughthe addition of thermosetting fibers or particles followed by heattreatment, by the addition of crosslinking agents followed by propercuring or heat treatment, by the addition of adhesives in the web, orother means known in the art. When fluid enters the basesheet 1,capillary forces can then wick the fluid into the absorbent material. Ifthe material is stabilized, it will be less likely to lose itscapillarity upon wetting but can continue to wick and retain fluidseffectively.

[0160] The hydrophobic fibers 50 may be applied in isolated orinterconnected patches along the uppermost surfaces of the hydrophilicbasesheet, or, in the case of a relatively flat basesheet, they may beapplied in a specific pattern to provide either isolated orinterconnected patches of such material, or a combination of isolatedand interconnected regions, preferably elevated relative to thesurrounding untreated basesheet such that skin adjacent to the covermaterial will preferentially contact and sense the soft hydrophobicregions. Preferably, the fibers have a denier less than about 9, morespecifically less than about 6, more specifically less than about 5, andmost specifically from about 1 to about 5. Suitable polymers includeethylene/propylene copolymers, polyester copolymers, low-densitypolyethylene, acrylic, ethylene/vinyl acetate copolymer, polyethylene,polypropylene, chlorinated polyethylene, polyvinyl chloride, polyamide,high density polyethylene, linear low-density polyethylene, and thelike. Conjugate fibers such as bicomponent sheath/core or bicomponentside-by-side fibers may also be used. Bicomponent fibers with arelatively low melting point material and a higher melting pointmaterial in a single fiber may be used by heating the fibers in contactwith the basesheet such that the low melting point material melts andadheres the unmelted higher melting point material to the basesheet.Although continuous filaments of fibers may be employed, the preferredfibers have lengths of from about 0.3 mm to about 10 mm, morespecifically from about 0.5 mm to about 5 mm, more specifically lessthan about 3 mm, and most specifically less than about 2 mm. Preferablythe attached fibers have at least one end which is free and can deformor deflect under shear to provide a soft, velvety feel. The fibersshould be fixedly attached such that they do not readily fall off orslough off excessively in use. The attached fibers may be applied toform a layer approximately one fiber diameter in depth or a layer havinga plurality of fiber diameters in thickness, including 2 to 100 fiberdiameters, more specifically 3 to 50 fiber diameters or morespecifically still 3 to 10 fiber diameters in depth.

[0161] The fibers may part of a preformed nonwoven web or may be loosefibers deposited through air laying and subsequent bonding, preferablyusing a patterned vacuum surface to apply the fibers in a desiredpattern, or else by applying a fairly uniform mat of short fibers ontothe surface of the basesheet and bonding only the fibers on theuppermost regions of the surface of the basesheet. The latter processmay include a heated nip in which the raised regions on the basesheetforce better contact between the deposited fibers and a textured heatedsurface, such that fibers become thermally bonded to the web only at thehighest points on the basesheet. The high spots on the textured heatingsurface or heating roll provide spot welding of the fibers onto thebasesheet.

[0162] A useful method of attaching hydrophilic fibers requires firstprinting or depositing binder material or adhesive onto the uppermostregions of a textured basesheet, such as by gravure printing, followedby exposure of the basesheet to loose fibers entrained in air, as in anair laying process, such that the fibers are retained by the bindermaterial on the printed regions but not retained elsewhere on thebasesheet. Unadhered fibers could then be removed by blowing of air orby vacuum, and then recycled. In this manner thin mats of loose, fluffyfibers could be deposited and attached on the desired locations on thebasesheet, preferably with minimal sheet penetration by the adhesive.

[0163] Fibers may be formed directly on the basesheet or depositedimmediately after formation using melt blown or spun bond processes,adapted to provide fibers only in desired regions. Alternatively, acontinuous thin, soft, bulky layer of a preformed melt blown or spunbond fibers may be cut to have apertures over the low regions of thetissue web and then positioned properly on the web and attached bythermal bonding or other means. In another embodiment, the fibers may beincorporated into a dilute aqueous slurry and applied onto thebasesheet. This may be done during the formation of the basesheet itselfwith a layered headbox, resulting in a unitary basesheet containing aportion of soft, hydrophobic fibers embedded in the upper layer of anotherwise cellulosic basesheet. Additional application ofwater-repellent agents at the uppermost regions of the contoured surfaceof the basesheet may then be needed to ensure that said uppermostregions are sufficiently hydrophobic.

[0164] Applicants have found that a contiguous web of hydrophobicfibers, such as spunbond or meltblown nonwoven web of synthetic fibers,can be especially advantageous for use as the hydrophobic matter of thepresent invention, offering economical processing and excellent comfort.For effective removal of menses, mucous, runny bowel movement, and otherviscous fluids, the nonwoven web should be provided with macroscopicapertures, slits, or other openings as shown in FIG. 14 to provide goodaccess to the hydrophilic basesheet for body exudates. The openings orapertures 61 in the nonwoven web 60 should overlay a portion of thedepressed regions in the hydrophilic basesheet such that fluid isrepelled by the most elevated portions of the surface contacting theskin and drawn toward depressed regions that are not in direct contactwith the skin.

[0165] Openings in a nonwoven web can be provided through pinaperturing; perf embossing and mechanical stretching of the web; diepunching or stamping; hydroentangling to impart apertures byrearrangement of the fibers; water knives that cut out desired aperturesor holes in the web; laser cutters that cut out portions of the web;patterned forming techniques, such as air laying of synthetic fibers ona patterned substrate to impart macroscopic openings, as disclosed by F.J. Evans in U.S. Pat. No. 3,485,706, issued Dec. 23, 1969, and U.S. Pat.No. 3,494,821, issued Feb. 10, 1970, both incorporated herein byreference; needle punching with sets of barbed needles to engage anddisplace fibers; and other methods known in the art. Pin aperturing ofnonwoven materials is described in commonly owned U.S. Pat. No.5,188,625, issued Feb. 23, 1993 to Van Iten, et al., herein incorporatedby reference.

[0166] Openings or apertures can be created in a way that permitsexcellent registration of apertures 61 with the depressed regions of athree-dimensional through-dried tissue web. A modified form ofhydroentangling may be especially useful in this regard. Such a processcomprises placement of a nonwoven web 60 on the same type ofthrough-drying fabric that is used to mold the associated basesheetduring through drying. With the nonwoven web on the through-dryingfabric, hydroentangling can be applied to drive fibers away from theelevated portions of the through-drying fabric, which will typicallycorrespond to the depressed regions of the fabric-side of thethrough-air dried sheet. If the tissue web is to be used with theair-side toward the body in the absorbent article, then the nonwoven webshould be placed on the backside of the through-drying fabric and thenhydroentangled, for the elevated portions of the backside of thethrough-drying fabric will generally correspond to the depressed regionsof the other side on which the tissue web is molded.

[0167] After hydroentangling on a through-drying fabric has provided thenonwoven web 60 with a pattern of apertures 61, the web can beregistered with the through-dried tissue to put the apertures over thedepressed regions to result in effective intake into the hydrophilicdepressions while maintaining hydrophobic material on the elevatedportions of the basesheet. Registration can be achieved with photoeyesand image analysis software or other mechanical means known in the artto control the position of the nonwoven web as it is placed on themolded basesheet by automated equipment.

[0168] Preferably, the openings are provided in a regular pattern overat least a portion of the topsheet of the absorbent article.

[0169] Wicking of fluids into the apertures toward the hydrophilicbasesheet can be enhanced by modification of the surface chemistry ofthe hydrophobic nonwoven web in the area of the apertures, such as byaddition of surfactants to the nonwoven web in the vicinity of aperturesor oxidation of fibers by plasma or other treatment. Alternatively,cellulosic fibers or other hydrophilic matter could be added to theregion of the apertures to enhance wicking. For example, cellulosicfibers could be added to the periphery of the apertures to enhancewicking.

EXAMPLES Example 1

[0170] To demonstrate an example of a textured, wet resilient absorbentweb with improved dry feel, a suitable basesheet was prepared andmodified by addition of hydrophobic material in the form of paraffin.The basesheet was produced on a continuous tissue making machine adaptedfor uncreped through-air drying, similar to the machine configurationshown in FIG. 4. The machine comprises a Fourdrinier forming section, atransfer section, a through-drying section, a subsequent transfersection and a reel. A dilute aqueous slurry at approximately 1%consistency was prepared from 100% spruce bleached chemithermomechanicalpulp (BCTMP), pulped for 20 minutes at about 4% consistency prior todilution. The spruce BCTMP is commercially available as Tembec 525/80,produced by Tembec Corp of Temiscaming, Quebec, Canada. Kymene 557LX wetstrength agent, manufactured by Hercules, Inc., Wilmington, Del., wasadded to the aqueous slurry at a dosage of about 20 pounds of Kymene perton of dry fiber. The slurry was then deposited on a fine forming fabricand dewatered by vacuum boxes to form a web with a consistency of about12%. The web was then transferred to a transfer fabric (Lindsay Wire952-505) using a vacuum shoe at a first transfer point with nosignificant speed differential between the two fabrics. The web wasfurther transferred from the transfer fabric to a woven through-dryingfabric at a second transfer point using a second vacuum shoe. Thethrough drying fabric used was a Lindsay Wire T-116-3 design (LindsayWire Division, Appleton Mills, Appleton, Wis.), based on the teachingsof U.S. Pat. No. 5,429,686 issued to Kai F. Chiu et al. The T-116-3fabric is well suited for creating molded, three-dimensional structures.At the second transfer point, the through-drying fabric was travelingmore slowly than the transfer fabric, with a velocity differential of2.8%. The web was then passed over a hooded through-dryer where thesheet was dried. The hood temperature was approximately 200° F. Thedried sheet was then transferred from the through-drying fabric toanother fabric, from which the sheet was reeled. The pilot paper machinefor producing the uncreped paper was operated at a speed ofapproximately 20 feet per minute. The basis weight of the dry basesheetwas approximately 39 gsm (grams per square meter). The sheet had athickness of 0.64 mm when measured with a platen gauge at 0.05 psi, fora dry bulk of 16.4 cc/g. The Surface Depth is about 0.42 mm.

[0171] Samples of the basesheet were conditioned under Tappienvironmental conditions for several days, then cut to a number of 6in×12 in sheets which were then treated with paraffin wax using avariety of methods. A rectangular slab of Gulfwax™ paraffin for homecanning was used to apply a small quantity of wax on the fabric sidesurface of the uncreped basesheet produced as described above. Severalbasesheet samples were heated individually on a Corning PC-351 hot plateset at a low power level of 2.5. The samples were held in light contactwith the heated surface by hand for 5 to 10 seconds, then removed andplaced on a table. The slab of wax was them immediately dragged over theheated sample surface to deposit a small quantity of wax on the mostelevated regions of the upper surface. In one version, the fabric sideof the basesheet was in contact with the heated surface, while in asecond version, the air side of the basesheet was heated. In applyingthe wax, the slab was held at about a 30° angle relative to the planeand the lower end of the slab was placed on the basesheet. The slab wasthen dragged with light force (estimated at about 0.5 to 1 pound) overone entire surface of the basesheet such that the contacting end of theslab was the trailing edge. Care was taken to apply the wax uniformly.The objective was to avoid melting the wax since the melted wax wouldimpregnate the basesheet and not remain on the surface, but tofacilitate the deposition of wax onto the basesheet through heat.Heating and wax treatment was done successively on sections about3-inches square or 6-inches square until the entire basesheet sample wastreated. The wax slab was weighed before and after application. Thetypical amount of wax applied to the 6 in×12 in basesheet was about 0.06g.

[0172] Upon subsequent wetting of the resulting absorbent web, minuteupper sections of the wax-treated web appeared slightly lighter thanuntreated regions, as if the wax had trapped some air next to thefibers. Based on the physical appearance, it was evident that wax waspreferentially distributed on the uppermost regions of the basesheetsurface, occupying a small fraction of the total surface area estimatedto be about 10%.

[0173] Mean Rewet values for untreated and wax-treated samples are shownin Table 1. Also listed are mean Normalized Rewet values (Rewet dividedby the conditioned dry mass of the sample). The graph in FIG. 15 depictsthe mean values and the 95% confidence intervals about the means (1.96 *standard deviation/square root of sample size). The treatment withparaffin resulted in a significant decrease in Rewet. The decrease inRewet value is assumed to be indicative of a dryer feel if the tissuewere wetted in contact with skin, for less fluid could pass through thelocal, elevated hydrophobic barriers to contact the skin. Thewax-treated samples also felt slightly less gritty than the untreatedsamples, apparently due to some degree of lubricity afforded by theparaffin on the highest portions of the treated surface. TABLE 1 RewetValues for Example I Normalized Rewet Treatment Method Rewet Value, g(Rewet/Dry Mass) Untreated 0.446 0.706 Wax, air-side heat 0.390 0.629Wax, fabric-side heat 0.363 0.564

Example 2

[0174] In order to further illustrate this invention, uncrepedthroughdried tissue basesheet was produced using the methodsubstantially as described in Example 1. More specifically,single-layer, single-ply tissue was made from unrefined northernsoftwood bleached chemithermomechanical pulp (BCTMP) fibers. Afterpulping and dilution of the BCFMP fibers, Kymene 557LX was added at 20kilograms per metric ton of pulp. The forming fabric in this case was anAppleton Wire 94M fabric and the first transfer fabric was a Lindsay 956fabric. Rush transfer was performed at the first transfer point, duringthe transfer from the forming fabric to the Lindsay 956 transfer fabric.The degree of rush transfer was 35%. The differential velocity transferprocess used the vacuum shoe geometry taught in U.S. Pat. No. 5,667,636,issued Mar. 4, 1997 to S. A. Engel et al., previously incorporated byreference. At this second transfer point, from the transfer fabric tothe through-air drying, both fabrics were running at substantially thesame speed of about 40 feet per minute. The web was then transferred toa throughdrying fabric (Lindsay Wire T116-3). The throughdrying fabricwas traveling at a speed substantially the same as the transfer fabric.The web was then carried over a throughdryer operating at a hoodtemperature of about 315° F. and dried to final dryness of about 94-98percent consistency. The basis weight of the web was 60 gsm.

[0175] The resulting uncreped throughdried tissue basesheet was used inmeasurements of In-Plane Permeability using a stack of two disks,yielding a value of 1.87×10^(−10 m) ² Wet resiliency testing gave a WCB(Wet Compressed Bulk) value of 9.65 cc/g, a Springback of 0.889, and anLER of 0.824. The bulk measured at 0.1 psi was 16.2 cc/g.

[0176] After several weeks of storage under Tappi environmentalconditions, the basesheet was then treated with paraffin wax essentiallyas described in Example 1. Two strips were prepared, 12 inches×6 inches.For each strip, the fabric side of a 6-inch square region was heated incontact with the Corning PC-351 hot plate at a power setting of 2.5 forabout 5 seconds, then removed and placed fabric-side up on a flatsurface. A slab of paraffin wax was then dragged over the surface todeposit about 0.06 g of wax on the surface of the first strip and 0.07 gof wax on the surface of the second. The two strips were then cut into4-inch×6-inch segments. All segments from the first strip (labeled 1A,1B, and 1C) were tested for Rewet and one segment from the second stripwas tested in addition to 3 similar untreated strips of the samebasesheet (labeled 3, 4, and 5). Results are shown in Table 2. Rewetvalues for the waxed segments were significantly lower than theuntreated samples, with the exception of segment 1A, which had a valuesimilar to untreated samples. This sample was excessively wet, beyondthe recommended range for the test, so the additional available moisturemay have inflated the Rewet value. However, it is suspected that thewaxing operation may have been performed poorly in the region that wouldlater be in contact with the Whatman filter paper during testing. Themean Rewet for the waxed samples, excluding sample 1A, is 0.467 gcompared to the untreated mean of 0.689 g, an apparent reduction of 32%.Normalized Rewet also drops significantly due to hydrophilic treatment.Here, Rewet values less than 0.68 g are taken as evidence of improveddry feel. TABLE 2 Rewet Values for Example 2 Dry Wet Normalized RewetSample Treatment Mass Mass Rewet, g (Rewet/Dry Mass) 1A Waxed 0.93 3.950.628 0.675 1B Waxed 0.94 3.82 0.438 0.466 1C Waxed 0.98 4.06 0.5250.536 2 Waxed 1.01 4.14 0.437 0.433 3 Unwaxed 0.97 3.98 0.680 0.701 4Unwaxed 1.00 4.06 0.692 0.692 5 Unwaxed 1.03 4.26 0.695 0.675

[0177] To determine if the small amount of presumably dominantly surfacewax applied to the textured basesheets had any adverse effect on totalabsorbent capacity, the tested segments were fully immersed in tap waterand then held by a corner and allowed to drip for 60 seconds, thenweighed. The “Dripping Wet Mass” for untreated samples 3 and 5 was 7.8and 8.3 g, respectively. The “Dripping Wet Mass” for samples 1A, 1B, and1C was 7.44, 7.55, and 7.9 g, respectively. For sample 2, it was 8.00 g.Given the variability and overlap of the data ranges for treated anduntreated samples, there is no clear evidence of a significant decreasein absorbent capacity of the waxed samples.

Examples 3-6

[0178] In order to further illustrate a method of making absorbent websof this invention, basesheets were produced using non-wet resilientnorthern softwood kraft fibers (NSWK), with and without a wet strengthagent (20 lbs Kymene/ton of fiber), and wet resilient fibers (spruceBCTMP), with and without a wet strength agent (20 lbs Kymene/ton offiber), using an uncreped throughdried process substantially as shown inFIG. 4.

[0179] The fiber was pulped at 4% consistency in the hydropulper for 30minutes. The fiber was pumped into a stock chest and diluted to 1.0%consistency. 20#/ton of Kymene 557 LX was added to the stock chest andallowed to mix for 30 minutes. A single-layer, blended sheet of 30 gsmdry weight was formed on an Albany 94M forming fabric and dewatered with5 inches (127 millimeters) of mercury vacuum. The forming fabric wastraveling at 69 fpm (0.35 meters per second). The sheet was transferredat a 15% rush transfer to a Lindsay 952-S05 transfer fabric traveling at60 fpm (0.30 meters per second). The vacuum in the transfer between theforming fabric and transfer fabric was 10 inches (254 millimeters) ofmercury.

[0180] The sheet was vacuum transferred at 12 inches (305 millimeters)of mercury to a throughdryer fabric (Lindsay T116-1) traveling at thesame speed as the transfer fabric, 60 fpm (0.30 meters per second). Thesheet and throughdryer fabric traveled over a fourth vacuum at 12 inches(305 millimeters) of mercury just prior to entering a Honeycombthroughdryer operating at 200° F. (93° C.) and dried to a final drynessof 94-98% consistency.

[0181] The basesheets were aged for over 5 days at less than 50%humidity at 70° F. (21° C.). The basesheets were tested for physicalcharacteristics in a controlled environment of 50%±2% humidity and 23°C.±1°. The wet and dry strength were Instron tested with a 3-inch (7.62cm) sample width, 4-inch (10.16 cm) jaw span at 10 in/min (25.4 cm/min)crosshead speed. Caliper was measured with the TMI tester at 0.289 psi.

[0182] Physical property results are shown in the table of FIG. 16.Example 6 exhibited substantially greater wet resiliency, as measured bythe Wet Wrinkle Recovery Test, than the other three samples. Inaddition, Example 6 also showed a high wet:dry ratio. The properties ofExample 6 in particular make it suitable for use as a basesheet that canbe calendered and later recover much of its original bulk upon wetting.When treated with hydrophobic materials such as silicones or talcumpowder, such a calendered absorbent web can provide high absorbency anda dry feel when the hydrophilic regions rise from the remainder of thesheet after wetting.

Examples 7-10

[0183] Further examples were carried out similar to those described inExamples 3-6, but for the purpose of exploring the basis weight effecton a bulky, absorbent, wet resilient structure. Four basis weight levelsof 30, 24, 18 and 13 gsm of 100% Spruce BCTMP with 20#/ton Kymene wereproduced.

[0184] The fiber was pulped at 4% consistency in the hydropulper for 30minutes. The fiber as pumped into a stock chest and diluted to 1.0%consistency. 20#/ton of Kymene 557 LX was added to the stock chest andallowed to mix for 30 minutes. A single-layer, blended sheet was formedon an Albany 94M forming fabric and dewatered with 4 inches (102millimeters) of mercury vacuum. The forming fabric was traveling at 69fpm (0.35 meters per second). The sheet was transferred at a 15% rushtransfer to a Lindsay 952-S05 transfer fabric traveling at 60 fpm (0.30meters per second). The vacuum in the transfer between the formingfabric and transfer fabric was 7 inches (178 millimeters) of mercury.The 13 gsm sample was produced without a rush transfer, the formingfabric was traveling at 60 fpm (0.30 meters per second), the same as thetransfer fabric and throughdryer fabric.

[0185] The sheet was vacuum transferred at 10 inches (254 millimeters)of mercury to a throughdryer fabric (Lindsay T116-1) traveling at thesame speed as the transfer fabric, 60 fpm (0.30 meters per second). Thesheet and throughdryer fabric traveled over a fourth vacuum at 11 inches(279 millimeters) of mercury just prior to entering a Honeycombthroughdryer operating at 260° F. (127° C.) and dried to a final drynessof 94-98% consistency.

[0186] The basesheets were aged for over 5 days at less than 50%humidity at 70° F. (21° C.). The basesheets were tested for physicalcharacteristics in a controlled environment of 50%±2% humidity and 23°C.±10. The wet and dry strength were Instron tested with a 3-inch (7.62cm) sample width, 4 inch (10.16 cm) jaw span at 10 in/min (25.4 cm/min)crosshead speed. The caliper was measured with the TMI tester at 0.289psi.

[0187] Physical property results are summarized in the table of FIG. 17.As shown, examples 7-10 exhibited high wet resiliency as determined bythe Wet Wrinkle Recovery Test and the Compressive Wet Resiliency tests.Materials such as the web of Example 10 are especially suitable as abasesheet to receive hydrophobic matter in the production of a dense,calendered absorbent web that can rapidly absorb liquid and then springback to a bulkier structure having hydrophilic material on the uppermostregions to provide a clean, dry feel. Typical commercial tissue andpaper towels generally have Wet Springback Ratios of less than 0.7, WCBvalues less than 6, and LER values less than 0.7. Likewise, suchmaterials tend to have In-plane Permeability values below 0.4×10⁻¹⁰ m².

Examples 11 and 12

[0188] For Examples 11 and 12, the fabric side of the basesheet ofExample 1 was treated with adhesive sprays to create scatteredhydrophobic regions, some of which were further treated with hydrophobicpowder. For Example 11, a spray can of 3M #72 Pressure SensitiveAdhesive was used to randomly cover about 30% of the surface area of thebasesheet with the blue, flexible, soft, and low-tack adhesive material.Tack was further reduced by sprinkling a small quantity of lycopodiumpowder (also known as club moss spores, commercially available from EMScience, Gibbstown, N.J.) on one portion of the web and talc powder onanother portion to selectively adhere to the adhesive and remove thetacky sensation. Unattached powder was shaken off. For Example 12, thespray adhesive used was 3M #90 High Strength Adhesive, which wasrandomly and lightly sprayed to yield scattered patches about ½ to 1inch in diameter containing adhesive on the upper surface. Tack wasagain reduced by sprinkling talk or lycopodium powder on variousportions of the web and removing excess powder. When the webs werewetted, the hydrophobic regions containing adhesive and hydrophobicpowder felt somewhat drier than the untreated regions. Theadhesive-containing regions of Example 12 were noticeably stiffer thanthe surrounding basesheet and would be unsuitable for many products. Thelower viscosity of the adhesive used in Example 12 also resulted inrelatively more penetration of the adhesive into the absorbent webrelative to Example 11, so the adhesive patches of Example 12 appearedlighter than the surrounding untreated regions when the absorbent webwas fully wetted with water.

Example 13

[0189] Additional uncreped, through-air dried basesheets were madeaccording to Example 2. Example 13 differed in having 10 pounds ofKymene per ton of dry fiber in the furnish, had 15% rush transfer, andcomprised 75% northern softwood kraft fibers and 25% spruce BCTMP. Aswith Example 2, the basis weight was 60 gsm and the through-air dryingfabric was a Lindsay Wire T116-3 fabric. The measured Wet SpringbackRatio was 0.839, WCB was 7.5 cc/g, and LER was 0.718. In-planePermeability was 0.84×10⁻¹⁰ m².

[0190] The basesheet of Example 13 could be made into a web of thepresent invention by blade coating the upper surfaces of the fabric sideof the basesheet with a flexible, hydrophobic, low-tack hot meltadhesive at elevated temperature immediately followed by air laying finesynthetic fibers having an average length of about 1 mm on theadhesive-containing side of the web, followed by light air jets to blowoff and recover unattached fibers. Cooling jets may be desired to removetack of the adhesive before reeling. Tack reduction of exposed adhesivemay also be accomplished by the addition of particulates entrained inair jets applied to the treated web, said particulates comprising talc,baking soda, titanium oxide, zinc oxide, miscellaneous fillers known inpapermaking, and the like.

[0191] The foregoing examples serve to illustrate possible approachespertaining to the present invention in which improved dry feel and otherproperties are achieved through novel combinations of resilient,textured basesheets with hydrophobic matter. However, it will beappreciated that the foregoing examples, given for purposes ofillustration, are not to be considered as limiting the scope of thisinvention which is defined by the following claims and all equivalentsthereto.

Example 14

[0192] A 0.6 osy polyethylene spunbond nonwoven web was laminated withconstruction adhesive to the fabric side of a 40 gsm uncreped,through-air dried web comprising 100% BCTMP spruce fibers and texturedby through drying on a Lindsay Wire T-216-3 fabric. A strip of airlaidcellulosic web was prepared that had been densified and stabilized withabout 1% thermoplastic fibers which melted during heating to hold thestrip at a constant density of about 0.2 g/cc. The 1-inch wide strip wasplaced underneath the uncreped basesheet with the attached nonwoven webon top. Fluid intake was tested by placing drops of dyed water on theupper surface. The water rapidly penetrated into the tissue basesheetand then into the airlaid strip, resulting in the majority of the fluidbeing held by the airlaid material. When colored drops of water wereplaced on the laminated web without an underlying airlaid absorbent, thefluid spread over a much greater area in the basesheet than when theairlaid strip was present.

[0193] A mixture of about equal parts egg white and water, with somegreen commercial food coloring added, was prepared to simulate theintake of viscoelastic fluids such as mucous or menses. The solution wasgently stirred to establish a uniform consistency. The solution was thenapplied as drops of about 0.3 ml to about 1 ml to the surface of theintake material with the airlaid strip underneath. Intake seemed veryslow or even completely impeded by the nonwoven material. The tip of aknife blade was then used to scratch away a small portion of thenonwoven web, resulting in an aperture about 0.2 mm wide and 2 mm long.A drop of the egg white solution applied to the aperture penetrated intothe hydrophilic within a few seconds, much more rapidly than without theaperture, yet still more slowly than the less viscous andnon-viscoelastic colored water.

Example 15

[0194] To demonstrate the potential of apertured nonwoven fabrics in thepresent invention, three polyethylene nonwoven spunbond webs wereacquired having basis weights of 0.4, 0.6, and 0.8 ounces per squareyard (osy). The webs were apertured using a roll device for twinaperturing. Metallic pins were mounted in holes in curved metal platesthat could be bolted onto the midsection of an upper roll. Matchingmetal plates with holes mounted to the lower roll received the uppertapered portion of the pins in the upper roll. Two different pindiameters were used, 0.109-inches and 0.187-inches. The holes forreceiving and holding pins were arrayed in a bilaterally staggered grid.The 0.187-inch pins were placed into every hole in the array over atwo-inch wide strip around the upper roll. Roll perimeter is 36 inches.The 0.187-inch pins were thus spaced apart at about 0.25-inch intervalsfrom center to center along any row. The 0.109-inch pins were spacedapart over a 4-inch wide strip of bilaterally staggered holes, with pinsloaded only in alternating rows and in any row containing pins, loadedonly into every other hole of that row. With 11 pins in each 4-inch widerow, the loaded 0.109-inch pins are spaced apart by about 0.4-inchesfrom center to center. To improve the quality of the aperturing, theupper roll containing the pins is heated to about 200° F. and the lowerroll, which contacts the nonwoven web, is electrically heated to 150° F.These are temperatures measured inside the roll. Using a surfacethermocouple, the upper surface temperature of the upper roll wasmeasured at 150-158° F. Using the 0.109-inch pins first, the aperturingdevice was driven at 50 fpm and used to aperture lengths of polyethylenespunbond material having a basis weight of 0.4, 0.6, and 0.8 osy (ounceper square yard). Then the plates containing pins were switched topermit aperturing with the 0.187-inch diameter pins, also at 50 fpm andall three spunbond basis weight materials were apertured. The aperturednonwoven web appeared soft and suitable for use as a feminine carematerial. Samples of the nonwoven webs were then cut and placed onsections of uncreped, through-dried material made according to Wendt etal., previously incorporated by reference, and textured onthree-dimensional through drying fabric from Lindsay Wire according toWendt et al. and Chiu et al., also previously incorporated by reference.

[0195] Though 3M pressure sensitive spray adhesive was used at one pointto join the tissue basesheet and the nonwoven web, joining the aperturednonwoven to the textured uncreped tissue web was simplified by a naturalmechanical affinity of the tissue surface for the loopy nonwovensurface. Engagement of fibrils apparently allows the nonwoven layer toadhere reasonably well, though it IS preferred to create a moreintimately bonded structure through any of adhesive bonding, ultrasonicbonding, thermal bonding, and the like.

Example 16

[0196] Composite topsheet structures were prepared by adhering theapertured webs of Example 15 to textured, uncreped, through air driedbasesheets, similar to those described in Examples 1-10. Adhesion wasachieved with a specialty adhesive transfer paper comprising a coatedrelease paper printed with dots of adhesive, such that the dots could betransferred to other surfaces by mild application of pressure. A hotmelt construction adhesive was used, National Starch #5610, printed on acoated release paper via screen printing with a New England Rotaryscreen, 40-NERO-SF0001. To join an apertured nonwoven web to thetextured tissue paper, the adhesive transfer paper was placed with theadhesive dots in contact with textured tissue and then pressed lightlywith a rubber roller at a load of less than 0.5 pounds per linear inchsuch that the web was not substantially flattened by the roller and suchthat a portion of the adhesive dots transferred to the most elevatedportions of the web. The apertured nonwoven web was then superposed onthe tissue. In placing the nonwoven web on the tissue web, the side ofthe nonwoven web that contacted the tissue was the side which was awayfrom the roll holding the pins during the pin aperturing process. Thistissue-facing side of the nonwoven web had protrusions surrounding eachaperture where the pin had forced some of the polyolefin material out ofthe plane of the nonwoven web during the pin aperturing process. In somecases, it may be preferably that such protrusions should resideprimarily in depressed regions of the underlying tissue web to provide anearly continuous material bridge from the body-facing side of thenonwoven web to the tissue surface, such that fluid does not need tocross any significant interfacial gaps between the two or more layers ofthe topsheet.

[0197] For these examples, only 0.4 osy basesheet nonwoven spunbond webswere used. The basesheets were all unlayered, uncreped, through-airdried tissue webs made according to the principles given in Examples1-10, with the exception that basis weight, fiber type, rush transfer,and fabric types were varied. “High texture” refers to webs made withabout 30% rush transfer onto a Lindsay Wire T-116-3 fabric as thetransfer fabric, followed by through drying on a T-216-3 fabric. “Flat”tissue was through dried on a traditional flat through drying fabriclacking high surface depth. “Medium texture” refers to webs made with 8%rush transfer onto a Lindsay Wire T-216-3 fabric as the transfer fabric,followed by through drying on a Lindsay Wire T-116-3 fabric. All webshad about 20 lb Kymene per ton of fiber added for wet strength. Thefollowing combinations of nonwoven and basesheet were tested: TABLE 3Composites tested for intake. Sample Aperturing Basesheet 1 none 30 gsm,100% BCTMP, high texture 2 0.109″ pins 30 gsm, 100% BCTMP, high texture3 0.187″ pins 30 gsm. 100% BCTMP, high texture 4 0.187″ pins 30 gsm,100% BCTMP, flat 5 0.187″ pins 30 gsm, 100% BCTMP, high texture 6 0.187″pins 50 gsm, 50% bleached northern softwood, 50% mercerized bleachedsouthern softwood, medium texture 7 0.187″ pins 30 gsm, 100% BCTMP, flat

[0198] In some cases, the cover material was combined with a thinabsorbent layer consisting of another uncreped, through-air dried sheetor an air-laid strip. These absorbent layers include:

[0199] Abs. A: a “high texture” 100% BCTMP web (Sample 1 of Table 3)

[0200] Abs. B: a “flat” 100% BCTMP web (Sample 4 of Table 3);

[0201] Abs. C: a 100% BCTMP uncreped web through-dried on a Lindsay Wire134-10 fabric;

[0202] Abs. D: a “medium texture” web comprising bleached softwood(Sample 6 of Table 3)

[0203] In addition, the airlaid strip of Example 14, having a basisweight of about 200 gsm, was also used in some tests. The absorbentlayer was simply placed beneath the composite cover and was not joinedmechanically or with adhesives. In some cases, light adhesive might bedesirable to hold the cover onto the absorbent core.

[0204] To demonstrate the suitability of the apertured webs of Example15 for intake of menses, a simple menses simulant was used. The simulantwas a 50:50 mixture of fresh egg whites and water, with added fugitivedye. The mixture was prepared by separating the egg whites from theyolks for two large eggs (Sparboe Farms, Litchfield, Minn.) that hadbeen removed from refrigeration and placed in a room with a temperatureof approximately 72° F. for six hours. The egg white mass was 60.0 g. Anadditional 60 g of deionized water was added to the egg whites in a 250ml beaker and stirred vigorously in the beaker with a laboratory spatulafor about 3 minutes, taking care to prevent froth formation. Theresulting mixture appeared slightly turbid and still showed signs ofproteinaceous strands in the fluid having a different refractive indexthat other parts of the solution. An additional 2 ml of a dye solutionwas stirred in gently. The dye solution was prepared by adding 40 ml ofVersatint Purple II due (Milliken Chemical, Inman, S.C.) to 1000 ml ofdeionized water.

[0205] The colored egg white solution was applied to the surface of thecomposite topsheet material with an Eppendorf pipette set to apply 0.5ml droplets. The droplet was applied to the upper surface of thetopsheet within a 3 second interval, taking care to apply the dropgently and smoothly. Initially the drop balled up, resting on thenonwetting surface as a flattened sphere several millimeters indiameter, broad enough to engage at least one aperture, typicallyregardless of where the drop was placed. Then visual observation wasused to identify the time required for wicking to occur in the plane ofthe underlying basesheet, and the additional time after the onset ofwicking for the drop to be substantially removed from the surface of thenonwoven web, such that essentially no remaining liquid remainednoticeably elevated above the plane of the nonwoven web. The first time,the time for visible wicking to begin, is termed the “entry time,” andwas detected when colored fluid could be seen extending horizontally inthe basesheet beyond the margins of the drop on top. The second time,the time for substantial removal of the liquid from drop on the nonwovensurface is the “wicking time.” The sum of the two times is the “intaketime.” Results are shown for several trials in Table 4. Best resultswere obtained with the larger pin apertures. With the smaller apertures,the hydrophobic fibers in the protrusion on the back side of the webformed during aperturing may have become flattened to partially closeoff apertures during attachment to the uncreped tissue web. TABLE 4Intake results for egg-white solutions for the composites of Table 3.Run Sample Entry time (s) Wicking time (s) Intake time (s) 1 1 >500NA >500 2 2 >500 NA >500 3 3 70 90 160 4 3 + Abs. A 20 80 100 5 4 + Abs.B 10 50 60 6 4 + Abs. B 0 25 25 7 5 + Abs. C 10 30 40 8 5 + Abs. C 0 4040 9 6 + Abs. D 5 35 40 10 7 about 200 about 200 about 400 11 4 + airlaid 10 150  160 12 4 + air laid >500 NA >500 13 5 + Abs. C 10 70 80 146 + air laid 5 200  205 15 6 + air laid >500 NA >500

[0206] It is believed that intake rates could be increased significantlyby increasing the exposed area of the basesheet.

[0207] By placing drops of the egg white solution directly on BCTMP andbleached softwood uncreped sheets, it was observed that BCTMP offersmore rapid intake, apparently because of the more open pore structure ofthe BCTMP sheet. Densified air laid strips with a density of about 0.2cc/g also gave rapid intake of the solution.

Example 17

[0208] The ability of the present invention to serve as an improvementover apertured films can be envisioned in this example, wherein a moisthydrophilic basesheet is provided with a non-planar apertured structureand then noncompressively dried to impart high wet resiliency, followedby printing or coating of hydrophobic matter on the most elevatedregions of the body-contacting side of the apertured web, resulting in acomposite material having hydrophilic apertures and a hydrophobic uppersurface. In particular, a soft, flexible web of basis weight from about10 gsm to about 100 gsm, more preferably from about 20 gsm to about 50gsm, during manufacture is apertured before the web has dried to aboveabout 60% solids, and preferably before the web has dried above about40% solids. The web may be relatively flat or textured prior toaperturing. Aperturing can be done by protrusions on a roll contactingthe body side of the web while residing on a surface having matingdepressions, such that intermeshing of the protrusions and thedepressions causes apertures to descend away from the body-contactingside of the web to create a non-planar, three-dimensional topographywith regions of the web adjacent the apertures having some z-directionfiber orientation. Apertures in the basesheet can also be created byneedling, perf-embossing, stamping, or differential air pressure.Differential air pressure can be used when the web resides on aperforated but otherwise low-permeability carrier. The weak, moist webresiding on a perforated surface permits air pressure to cause portionsof fibers over the perforations to deflect and break free from the planeof the web and to descend partly in the z-direction. After the 3-Dapertures are created in the moist state, the web should be dried tocompletion without significantly disrupting the perforated or aperturedstate it has achieved. The structure of the web will then have high wetresiliency, particularly if low yield fibers or wet strength additivesare used. As a result, the basesheet is provided with apertures and thelower surface of the basesheet is provided with fibrous protrusionsdescending from the basesheet which are adjacent to the apertures andmay surround or partially surround the apertures, forming hydrophilicaperture walls. The protrusions or aperture walls, by virtue of beingdried in their three-dimensional state, also have good wet resiliency,or a tendency to maintain the form and orientation in which they weredried even after being wetted, especially if high yield fibers or wetstrength agents were used in making the web. Preferably, the apertureshave an open area of at least 15% and more preferably at least 30%, andhave a characteristic or effective diameter preferably of from about 0.2mm to about 4 mm, more specifically from about 0.3 mm to about 2 mm, andmost specifically about 0.5 mm or greater.

[0209] After non-compressive drying, the body-contacting side of the web(the side remote from the descending sides of the apertures) is treatedwith hydrophobic matter. This may be printed onto the web indiscontiguous drops or fine spaced apart regions. Alternatively, the webmay be coated or printed by a smooth printing surface having a film ofthe hydrophobic matter in the molten, liquid state, or slurry state.Waxes or mixtures of wax, oil, and opacifiers may be especiallypreferred. The resulting structure has hydrophobic elevated regionswhile the walls of the apertures descending away from the hydrophobicmatter are still hydrophobic. The hydrophobic matter is intimatelybonded to the surface of the hydrophilic web. Because the basesheet isproviding structural integrity, the hydrophobic matter can be continuesbut weak or discontiguous, and generally would not be expected to becapable of being removed from the basesheet without being severelydamaged or disintegrating. It provides a dry feel adjacent the body and,if properly selected, can enhance the soft, pleasant feel of the cover.The underlying basesheet provides excellent absorbency and providesconduits like traditional apertured films for flow direct to theabsorbent core. However, in-plane wicking and flow channels underneaththe basesheet will provide for good fluid handling and absorbentcapacity.

[0210] It will be appreciated that the foregoing examples, given forpurposes of illustration, are not to be construed as limiting the scopeof this invention, which is defined by the following claims and allequivalents thereto.

We claim:
 1. An absorbent web having a dry feel when wet comprising: a) an inherently hydrophilic basesheet comprising papermaking fibers and having an upper surface and a lower surface, said upper surface having elevated and depressed regions; and b) hydrophobic matter deposited preferentially on the elevated regions of the upper surface of said basesheet.
 2. The absorbent web of claim 1 wherein said basesheet is a wet-laid tissue sheet.
 3. The absorbent web of claim 1 wherein said basesheet is an airlaid structure.
 4. The absorbent web of claim 1 further characterized by a Wet Springback Ratio of about 0.7 or greater.
 5. The absorbent web of claim 1 wherein the hydrophobic matter is discontiguous.
 6. The absorbent web of claim 1 further characterized by a Rewet value of about 0.65 g or less and a Normalized Rewet value of about 0.6 or less.
 7. The absorbent web of claim 1 wherein said basesheet has an Overall Surface Depth of about 0.2 mm or greater, an In-Plane Permeability of at least 0.5×10⁻¹⁰ m², and a Wet Compressed Bulk of about 5 cc/g or greater.
 8. The absorbent web of claim 1 wherein said hydrophobic matter comprises synthetic fibers fixedly attached to the upper surface of said basesheet such that about 50% or less of the surface area of the basesheet is covered with the synthetic fibers.
 9. The absorbent web of claim 1 further comprising hydrophobic matter on a portion of the lower surface of said basesheet.
 10. The absorbent web of claim 1 wherein said web has an Overall Surface Depth of about 0.2 mm or less while dry and an Overall Surface Depth of about 0.3 mm or greater when wetted to a moisture content of 100%.
 11. The absorbent web of claim 1 wherein said basesheet has a wet:dry tensile ratio of at least 0.1.
 12. The absorbent web of claim 1 wherein said elevated regions comprise from 5 to 300 protrusions per square inch having a characteristic height of at least 0.2 mm relative to said depressed regions.
 13. The absorbent web of claim 1 wherein at least 30% of the upper surface of said basesheet remains substantially free of hydrophobic matter and said web has a Rewet value of 0.6 g or less.
 14. The absorbent web of claim 1 wherein essentially all of said hydrophobic matter resides above the 50% material line of a characteristic cross-section of said web.
 15. The absorbent web of claim 1 further comprising superabsorbent particles attached to said basesheet.
 16. An absorbent dual-zoned web providing a dry feel in use, said web having an upper surface comprising a plurality of hydrophobically treated regions surrounded by inherently hydrophilic cellulosic regions, wherein upon wetting said web expands such that the hydrophobically treated regions are preferentially elevated relative to said hydrophilic regions.
 17. A calendered hand towel comprising the web of claim
 16. 18. An absorbent web having a Rewet value of about 1 g or less, comprising: a) an inherently hydrophilic basesheet comprising papermaking fibers and having an upper surface and a lower surface, said upper surface having elevated and depressed regions with an Overall Surface Depth of 0.2 mm or greater in the uncalendered and uncreped state, said basesheet further having a Wet Compressed Bulk of at least 6 cc/g; and b) hydrophobic matter deposited preferentially on the elevated regions of the upper surface of said basesheet.
 19. The absorbent web of claim 18 wherein said basesheet is an airlaid structure.
 20. An absorbent article comprising the absorbent web of claim
 18. 21. An absorbent web having a dry feel when wet, comprising: a) an inherently hydrophilic basesheet comprising papermaking fibers and having an upper surface and a lower surface, said upper surface having elevated and depressed regions with an Overall Surface Depth of about 0.2 mm or greater; b) a substantially contiguous network of hydrophobic fibers having a plurality of macroscopic openings attached to the upper surface of said basesheet such that a portion of the depressed regions of the basesheet are aligned with openings in the overlaying network of hydrophobic fibers to allow body exudates to pass through the macroscopic openings into the basesheet.
 22. The absorbent web of claim 21 wherein said network of hydrophobic fibers comprises a plurality of macroscopic openings having a characteristic width of about 0.2 mm or greater.
 23. The absorbent web of claim 21 wherein said basesheet is further characterized by a wet:dry tensile strength ratio of at least about 0.1 or greater and a Wet Springback Ratio of about 0.55 or greater.
 24. The absorbent web of claim 21 further characterized by a Rewet value of about 0.65 g or less and a Normalized Rewet value of about 0.6 or less, said basesheet further comprising about 20% or greater by weight high yield pulp fibers.
 25. The absorbent web of claim 21, wherein the superficial basis weight of said hydrophobic matter is from about 1 to about 10 gsm and said basesheet has a basis weight of from about 10 to about 70 gsm.
 26. The absorbent web of claim 21 wherein said basesheet is an airlaid structure.
 27. The absorbent web of claim 21 wherein said basesheet is a wet-laid web.
 28. The absorbent web of claim 1 or 21, wherein said basesheet further comprises apertures and said lower surface of the basesheet further comprises wet-resilient protrusions adjacent said apertures.
 29. An absorbent web having a dry feel when wet, comprising: a) an inherently hydrophilic basesheet comprising papermaking fibers and having an upper surface and a lower surface, said upper surface having elevated and depressed regions, said basesheet further having a wet:dry tensile ratio of at least 0.1; and b) a contiguous network of hydrophobic matter deposited preferentially on the elevated regions of the upper surface of said basesheet.
 30. An absorbent article with a body-side liner comprising the web of either claim 21 or claim
 29. 31. An absorbent article comprising a liquid impermeable backsheet, a cellulosic absorbent core in superposed relation with said backsheet, and a liquid permeable absorbent web, said absorbent web comprising an inherently hydrophilic basesheet comprising papermaking fibers, said basesheet having an upper surface and a lower surface, said upper surface having elevated and depressed regions, further comprising an apertured contiguous web of hydrophobic nonwoven material attached to the upper surface of the basesheet such that a portion of said apertures overlay the depressed regions of the basesheet, wherein the basesheet is superposed on the absorbent core with the lower surface of the basesheet facing the absorbent core.
 32. An absorbent article comprising a liquid impermeable backsheet, a cellulosic absorbent core in superposed relation with said backsheet, and a liquid permeable absorbent web, said absorbent web comprising an inherently hydrophilic basesheet comprising papermaking fibers and having a wet:dry tensile ratio of at least 0.1, said basesheet having an upper surface and a lower surface, said upper surface having elevated and depressed regions and hydrophobic matter deposited preferentially on the elevated regions, wherein the basesheet is superposed on the absorbent core with the lower surface of the basesheet facing the absorbent core.
 33. An intake material for an absorbent article comprising an apertured nonwoven upper layer and a three-dimensional through-dried lower cellulosic basesheet layer having a pattern of elevated and depressed regions, wherein the apertures of the upper layer are substantially registered with depressed regions in the lower cellulosic layer.
 34. The intake material of claim 33, wherein the nonwoven upper layer is a hydroentangled web of synthetic fibers.
 35. An absorbent article comprising the intake material of claim 33 and a densified absorbent material adjacent to the basesheet and remote from the nonwoven upper layer, wherein said densified absorbent material has a density greater than the density of the basesheet.
 36. A method for producing an absorbent web having a dry feel when wet comprising the steps of a) preparing an inherently hydrophilic basesheet comprising papermaking fibers and having an upper surface and a lower surface, said upper surface having elevated and depressed regions; and b) depositing hydrophobic matter preferentially on the elevated regions of the upper surface of said basesheet.
 37. The method of claim 36, wherein said step of preparing the basesheet comprises the steps of depositing an aqueous slurry of papermaking fibers on a foraminous web to produce an embryonic web; molding said web on a three-dimensional substrate; and drying said web.
 38. A method for producing an absorbent article comprising the steps of: a) preparing a wet resilient, cellulosic basesheet having elevated and depressed regions with an Overall Surface Depth of at least 0.2 mm and having an upper surface and a lower surface; b) integrally attaching a contiguous, fibrous nonwoven web having a plurality of openings onto the upper surface of the cellulosic basesheet such a portion of the openings are superposed over the depressed regions of the cellulosic basesheet; c) attaching the lower surface of the basesheet to an absorbent core and an impervious web, such that the absorbent core is sandwiched between the impervious web and the basesheet.
 39. A method for producing an intake material for an absorbent article, comprising the steps of a) forming an embryonic paper web from an aqueous slurry of papermaking fibers; b) through-drying the embryonic paper web on a three-dimensional through-drying fabric having a pattern of elevated and depressed regions; c) completing the drying of the web; d) aperturing a nonwoven web by means of hydroentangling, wherein the nonwoven web overlays a carrier fabric having substantially the same pattern of elevated and depressed regions as the through-drying fabric of step (b); e) joining the apertured nonwoven web with the through-dried paper web such that the apertures of the nonwoven web are substantially aligned with the depressed regions of the through-dried paper web. 